Quality issues and leakage analysis of mechanical seals for gear oil pumps

{1} The principle of gear pump mechanical seal is to achieve a tight fit between the sealing pairs through elastic components and medium pressure. When the equipment is running, the dynamic ring that rotates with the shaft and the static ring connected to the sealing shell produce relative rotation, forming a stable liquid film between the sealing surfaces, thereby blocking medium leakage and achieving end face sealing effect

(1) There are problems with the manufacturing quality of sealing components

Insufficient hardness of sealing rings, poor sintering quality of graphite rings, and manufacturing quality problems of elastic components.

(2) Insufficient manufacturing accuracy

In the manufacturing of mechanical seals for gear oil pumps, high requirements are placed on the roughness and flatness of the sealing end face, which are important quality indicators for seals.

. If the roughness and flatness of the sealing surface do not meet the standard, it will seriously affect the stability of sealing use; In addition, the manufacturing accuracy of auxiliary seals is also important. For example, if the interference of the auxiliary seal ring of the moving ring is too large, it will jam the moving ring, making it unable to compensate for axial movement and leak. If the interference is too small, it will not be able to play a role in static sealing

{II} Analysis of Leakage Points in Gear Oil Pump Mechanical Seals

The dynamic ring of the mechanical seal is composed of fixed bolts, sealing rings, transmission seats, and springs, which are installed on the transmission shaft to achieve joint operation with the shaft body.

. The static ring is composed of anti rotation fixing bolts and sealing rings, installed on the machine sealing cover, and forms a whole with the gear oil pump housing, in a static state. After the installation of the mechanical seal is completed, it is necessary to rely on the pressure exerted by the internal working medium and the force exerted by the spring force provided by the dynamic ring spring to achieve tight compaction between the dynamic ring and the static ring. When the gear oil pump is in working condition, a thin liquid film is formed between the dynamic and static rings by the working medium, ensuring that the mechanical seal will not leak. This is the main seal of the mechanical seal. In addition, the sealing between the shaft sleeve and the moving ring, the mechanical seal static ring and the pressure cover, the shaft sleeve and the pump shaft are sealed with O-ring seals

The parts where mechanical seals may leak include: (1) the sealing point between the shaft sleeve and the shaft, which is a static seal. (2) The sealing of the contact surface between the dynamic and static rings is dynamic sealing. (3) The dynamic ring and shaft sleeve seals are static seals. (4) The seal between the static ring and the mechanical seal gland is a type of static seal. (5) The sealing point between the mechanical seal gland and the gear oil pump body is a static seal