1 Overview
A company's circulating pump is produced by the Changsha Pump Factory single-stage double suction centrifugal pump, Model 32SHA-10, the media for the production of ammonia and urea circulating water. The pump rotor from the impeller, shaft, flat key, left and right positioning sleeve and threaded sets of components. Although the impeller and the axis of the match for the gap with (φ165D / d), due to impeller and shaft with the inclusion of large (181335mm2), impeller holes, shaft and key position error, resulting in the demolition of the impeller more difficult. At the same time as the rotor running time is longer, positioning sleeve and the gap between the shaft has been the media corrosion and dirt deposition filled plug, positioning sleeve can not be removed separately, only with the impeller unloaded, thus increasing the impeller Disassembly difficulty. In view of the structural characteristics of the rotor and the actual use, we use the top pressure method and the temperature difference method with the demolition program, and achieved good results.
The demolition of the basic process is: First, the rotor is placed on a demolished tire, so that the impeller is fixed, and then apply a certain amount of top pressure on the shaft, while the impeller hub to heat the expansion of the shaft under the action of force and Impeller hole out.
2 demolition of the tire with the design
According to the rotor structure and stress analysis, taking into account the stability of the tire, bearing capacity and ease of production, the fetal frame with 16 channel welded together, the bottom frame with thick δ = 20 Q235 steel plate reinforcement , The tire with the upper part of the two beams using the activities of the push-pull structure, the material with 14 heavy rail.
When the demolition, the first rotor on the tire, and then beam on the impeller inlet end surface, the jack on the axis of the top of the pressure, the rotor vertically upward movement, when the beam and the upper part of the frame with the tire on both sides of the Fixed beam contact, it will play a role in limiting the impeller upward movement. As the jack below the rotor continues to exert pressure, when the top pressure exceeds the combined resistance between the impeller and the shaft, the impeller and shaft will slip and fall off.
3 top pressure and heating methods to determine
With the gap (mm) Jack (t) Heating time t (min)
T1t2
0.03-0.055063
0.06 to 0.085052
0.08 to 0.13051
Rotor in the demolition of the top of the pressure of the size of the heating temperature and the length of time is the key to whether the smooth removal of the rotor.
3.1 Determination of top pressure
Using the assembly theory to calculate, the removal of force:
P =? DL? Q? F
Where: D-mating surface diameter, m;
Length of mating surface, m;
Q-geometric error should be from the positive pressure, Pa;
F - coefficient of friction.
Calculated: demolition force P = 181335 × 10-6qf.
It can be seen from the above formula, shape and position error caused by the positive pressure q and friction coefficient f trace changes, will lead to a large difference in the demolition force, practice for long-term operation in the medium circulating pump rotor, the impeller Friction when the demolition is quite large, generally f take 2 to 8, q take 9.8 × 104 ~ 1.47 × 105, so Pmax = 213249.96N.
3.2 determine the heating method
For the structure of the impeller, combined with the actual production, we use two gas welding at the same time on the impeller hub heating, gas welding flame in the form of oxidation flame. Heating time is strictly controlled, if the heating time is short, the hole expansion is not enough, the impeller can not slip with the shaft; such as the heating time is too long, the impeller on the heat quickly passed to the shaft, the shaft is too much heat, the local temperature, Axis diameter increases, in theory, the performance of the axis of the warming rate of speed, the hub of the heating rate slowed down by the temperature difference caused by the wheel hole and the gap between the shaft is not increased but decreased, it is likely to produce interference fit , So that demolition can not be carried out.
4 Conclusion
Circulation pump impeller disassembly, the use of top pressure method and the temperature difference method, proved to be a safe, reliable, easy to use, but also greatly improve the efficiency of the demolition method. Its tire with a small volume, compact structure, mobile and flexible, can be used in the production site or repair workshop for the future overhaul of the circulating pump laid the foundation.
A company's circulating pump is produced by the Changsha Pump Factory single-stage double suction centrifugal pump, Model 32SHA-10, the media for the production of ammonia and urea circulating water. The pump rotor from the impeller, shaft, flat key, left and right positioning sleeve and threaded sets of components. Although the impeller and the axis of the match for the gap with (φ165D / d), due to impeller and shaft with the inclusion of large (181335mm2), impeller holes, shaft and key position error, resulting in the demolition of the impeller more difficult. At the same time as the rotor running time is longer, positioning sleeve and the gap between the shaft has been the media corrosion and dirt deposition filled plug, positioning sleeve can not be removed separately, only with the impeller unloaded, thus increasing the impeller Disassembly difficulty. In view of the structural characteristics of the rotor and the actual use, we use the top pressure method and the temperature difference method with the demolition program, and achieved good results.
The demolition of the basic process is: First, the rotor is placed on a demolished tire, so that the impeller is fixed, and then apply a certain amount of top pressure on the shaft, while the impeller hub to heat the expansion of the shaft under the action of force and Impeller hole out.
2 demolition of the tire with the design
According to the rotor structure and stress analysis, taking into account the stability of the tire, bearing capacity and ease of production, the fetal frame with 16 channel welded together, the bottom frame with thick δ = 20 Q235 steel plate reinforcement , The tire with the upper part of the two beams using the activities of the push-pull structure, the material with 14 heavy rail.
When the demolition, the first rotor on the tire, and then beam on the impeller inlet end surface, the jack on the axis of the top of the pressure, the rotor vertically upward movement, when the beam and the upper part of the frame with the tire on both sides of the Fixed beam contact, it will play a role in limiting the impeller upward movement. As the jack below the rotor continues to exert pressure, when the top pressure exceeds the combined resistance between the impeller and the shaft, the impeller and shaft will slip and fall off.
3 top pressure and heating methods to determine
With the gap (mm) Jack (t) Heating time t (min)
T1t2
0.03-0.055063
0.06 to 0.085052
0.08 to 0.13051
Rotor in the demolition of the top of the pressure of the size of the heating temperature and the length of time is the key to whether the smooth removal of the rotor.
3.1 Determination of top pressure
Using the assembly theory to calculate, the removal of force:
P =? DL? Q? F
Where: D-mating surface diameter, m;
Length of mating surface, m;
Q-geometric error should be from the positive pressure, Pa;
F - coefficient of friction.
Calculated: demolition force P = 181335 × 10-6qf.
It can be seen from the above formula, shape and position error caused by the positive pressure q and friction coefficient f trace changes, will lead to a large difference in the demolition force, practice for long-term operation in the medium circulating pump rotor, the impeller Friction when the demolition is quite large, generally f take 2 to 8, q take 9.8 × 104 ~ 1.47 × 105, so Pmax = 213249.96N.
3.2 determine the heating method
For the structure of the impeller, combined with the actual production, we use two gas welding at the same time on the impeller hub heating, gas welding flame in the form of oxidation flame. Heating time is strictly controlled, if the heating time is short, the hole expansion is not enough, the impeller can not slip with the shaft; such as the heating time is too long, the impeller on the heat quickly passed to the shaft, the shaft is too much heat, the local temperature, Axis diameter increases, in theory, the performance of the axis of the warming rate of speed, the hub of the heating rate slowed down by the temperature difference caused by the wheel hole and the gap between the shaft is not increased but decreased, it is likely to produce interference fit , So that demolition can not be carried out.
4 Conclusion
Circulation pump impeller disassembly, the use of top pressure method and the temperature difference method, proved to be a safe, reliable, easy to use, but also greatly improve the efficiency of the demolition method. Its tire with a small volume, compact structure, mobile and flexible, can be used in the production site or repair workshop for the future overhaul of the circulating pump laid the foundation.
Manufacturers recommend: Shenlong stainless steel fountain submersible pump
Keywords:Dismantling, Top Pressing Method and Temperature Difference Method of Large Pump
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