A. Inspection method of packing seal
1. Clean the filling box of the centrifugal pump and check the surface of the shaft for scratches, burrs, etc. The stuffing box should be clean and the shaft surface should be smooth.
2. Check the shaft runout. The unbalance of the rotor jump should be within the allowable range to avoid excessive vibration and unfavorable to the packing.
3. Apply a sealant or a lubricant compatible with the medium in the stuffing box and the shaft surface.
4. For the packing of the roll package, first take the wooden rod with the same root and the same size as the journal, wrap the packing around it, and then cut it with a knife. The knife edge is preferably 45° inclined.
5.The filler should be filled one by one, not a few loads at a time. The method is to take a filler, apply a lubricant, and hold one end of the filler interface with both hands, pull it in the axial direction to make it spiral, and then enter the journal from the slit casing. Do not pull in the radial direction to avoid the interface is not aligned.
6. Take a metal bushing of the same size as the stuffing box or a lower shaft hardness, push the packing into the deep part of the box, and apply a certain pressure to the bushing with the gland to pre-compress the packing. The pre-compression amount is 5%~10%, and the maximum is 20%. Rotate the shaft one more turn and remove the sleeve.
7. Fill the second and third roots in the same way. Note that when the number of fillers is 4~8, the interfaces should be staggered by 90° when filling; the two fillers are staggered by 180°; 3-6 are staggered by 120° to prevent leakage through the interface.
8. After the last packing is completed, the gland should be pressed tightly, but the pressing force should not be too large. At the same time, the shaft is rotated by hand, so that the assembly pressing force tends to parabolic distribution. Then relax the gland slightly.
9. Carry out the running test. If it can't be sealed, press some packing again; if the heat is too big, relax it. In this way, only when the droplet leakage and heat generation are small (the temperature of the filler part can only be 30 to 40 ° C higher than the ambient temperature), it can be put into use.
B. Technical requirements for the assembly of centrifugal pump packing seals. Installation of packing seals shall comply with the technical documents. If not specified, the following requirements should be met:
1. Check the radial runout of the shaft at the sealing part, and the allowable radial runout of the shaft is in the range of 0.03~0.08mm;
2. The diameter gap between the liquid seal ring and the sleeve is generally 1.00~1.50mm, and the diameter gap between the liquid seal ring and the stuffing box is generally 0.15~0.20mm;
3. The gap between the packing gland and the sleeve is generally 0.75~1.00mm, and the surrounding gap should be even;
4. The gap between the packing gland and the stuffing box is generally 0.10~0.30mm;
5. When there is a packing bottom ring, the diameter of the bottom ring and the sleeve is generally 0.70~1.00mm;
6. After the packing is pressed, the liquid sealing ring inlet hole should be aligned with the liquid sealing tube, or the liquid sealing ring should be slightly biased to the outside;
7. For the packing of the roll package, first take a wooden rod of the same size as the shaft, wrap the packing around it, and then cut it with a knife. The slit is preferably 45° inclined.
C. Technical standards for coupling overhaul
The small pump couplings mainly include rigid couplings, toothed couplings and flexible couplings: they are described as follows:
Rigid Coupling Rigid Couplings are generally used on centrifugal pumps with low power. Firstly, the connecting bolts and rubber elastic rings are removed during maintenance. For liquids with low temperature, the plane clearance of the two coupling halves is 2.2~4.2. Mm, when the temperature is high, it should be 1.55~2.05mm larger than the axis. The rubber elastic ring of the coupling should be 0.15~0.35mm smaller than the diameter of the perforation. At the same time, special tools must be used when disassembling and disassembling, keeping it clean and not scratching. Fourth, the toothed coupling toothed coupling is better in flexibility and has automatic alignment performance. The inspection is generally carried out as follows:
1. Check the meshing condition of the coupling tooth surface. The contact area is not less than 50% along the tooth height, not less than 70% along the tooth width. The tooth surface must not have severe pitting, wear and crack.
2. The full circle of the outer ring gear of the coupling is not more than 0.03mm, and the circular runout of the end face is not more than 0.02mm.
3. If you need to remove the ring gear, you must use special tools, not to knock, so as not to bend or damage the shaft. When reloading, the ring gear should be heated to about 200 ° C and then loaded onto the shaft. The interference between the outer ring gear and the shaft is generally 0.01~0.03mm.
4. When reloading the indirect cylinder or other parts, it should be assembled according to the original mark and data.
5. Tighten the bolt evenly with a torque wrench.
D. Diaphragm type flexible coupling
1. Clean and inspect the surface of the two coupling halves. There should be no cracks or abrasion on the surface. The surface matching the middle spacer should be smooth and burr-free. The coaxiality deviation of the coupling halves should be less than 0.003mm.
2. Clean and inspect the spring piece, no cracks or deformation.
3. Clean and inspect the bolts. The surface should be free from cracks, abrasion and deformation.
4. Correction requirements: axial ± 0.03mm, radial ± 0.05mm.
