Explanation of packing seal structure and packing seal princi
Among the sealing forms of melt gear pump, the combination of packing seal and mechanical seal is usually used. Compared with spiral seal, it has simple structure, easy disassembly and assembly, and can give full play to the advantages of packing seal and mechanical seal. Packing seal is a common form of shaft seal, but the selection of packing, sealing performance and structural design directly affect the efficiency of sealing.
By adjusting the pressure control screw, the pressure in the melt sealing cavity is slightly greater than the atmospheric pressure (generally 0.2~0.4 MPa), which is used to make the melt sealing cavity reach positive pressure without too high. The thread between the shaft sleeve and the seal seat is like a screw pump, pushing the leaked melt into the pump. The packing seal is equipped with a pre tensioning device, which prevents the melt from leaking outward and the air from penetrating into the thermoplastic extrusion pump through silicone oil. Silicone oil simultaneously lubricates the friction between packing and shaft.
Among the sealing forms of melt pump, the combination of packing seal and mechanical seal is usually used. Compared with spiral seal, it has simple structure, easy disassembly and assembly, and can give full play to the advantages of packing seal and mechanical seal. Packing seal is a common form of shaft seal, but the selection of packing, sealing performance and structural design directly affect the efficiency of sealing.
The essence of the packing seal of the gear melt pump is to use the soft characteristics of the sealing packing. Under the action of the axial compression force, the channel that may leak the melt is blocked radially. The force applied to the packing seal must make the contact stress between the packing and the sealing shaft surface generate, which can block the effect of the pressure of the sealed melt. Therefore, the radial contact pressure at the bottom of the stuffing box must be greater than or equal to the pressure of the sealed melt, which is a very important criterion in structural design. info@battemachinery.com