The axial clearance positioning of Roots blower is the key point in the maintenance of Roots blower during installation. Its installation quality is related to the stable operation of the equipment. However, the damage events of Roots blower caused by the inaccurate adjustment of axial clearance emerge in endlessly. Therefore, it is very important to master the skills of axial clearance adjustment of Roots blower. In the maintenance of rotating machinery and equipment, data should be the only reference standard, and any wrong method judged by human experience should be abandoned.
The main function of the axial positioning of Roots blower is that when the blower is running, the shaft system will produce linear expansion and body expansion due to the rotor heating. The volume expansion reserve is ensured by radial processing, and the linear expansion reserve is determined by axial positioning. If the axial reserve is too large, the fan efficiency will become low; The axial reserve is too small, and the fan casing and bearing will be heated and damaged.
The original radial gap value of the bearing is determined according to the accuracy grade of the bearing. If the outer end of the impeller is found to rub against the casing, remove the fan gear box cover, loosen the bolts on both ends of the fan casing, and remove the locating pin. Put the outer diameter gauge on the drive gear and the pulley (or coupling) at the other end.
Gently and symmetrically strike the gear and the belt pulley (or coupling) at the other end with a copper hammer. Measure with a feeler gauge every time you tap. Repeat until the clearance meets the requirements, and then tighten the shell bolts at both ends symmetrically.
If it is found that the end face of the impeller rubs against the side wall plate of the casing, the clearance between the impeller and the side wall of the casing can be detected with a feeler gauge, the screws for fixing the bearing cover can be pulled out, and padding paper can be added or extracted between the bearing seat and the bearing cover near the belt pulley (or coupling) end to adjust, so that the impeller can move axially. Depending on the measured clearance. After correction, talk again; Tighten the bolts symmetrically in order to fix the bearing cover
There are two main reasons for bearing end face wear. One is that foreign matters enter the end face of rotor and bearing seat, which is too rare to be analyzed here. The other is that the axial clearance is not enough, which causes the contact wear between the rotor and the bearing end face when the rotor expands online. We know that the molecules of any substance are doing irregular thermal movement, so the molecules have speed,
There is kinetic energy. Microscopically, the pressure of gas is the impact of a large number of molecules on the wall of the container, and the temperature is the measurement of the average kinetic energy of the thermal movement of a large number of molecules. The higher the temperature is, the greater the average kinetic energy of the thermal movement of the molecule, and the greater the speed of the molecule. We know that the greater the speed, the more violent the impact, that is, the greater the pressure of the gas. When the fan generates pressure, on the contrary, the gas will generate temperature. The temperature causes the rotor to stretch, and if the clearance is not enough, it will cause friction between the rotor and the casing.
At the same time, friction generates heat, which will increase the bearing temperature through heat conduction, thus damaging the bearing and sealing ring. The fan efficiency will be reduced if the axial clearance is too large. As Roots blower is a positive displacement fan, its wind pressure has something to do with the system, but has little to do with others. That is to say, it has a certain relationship with the characteristics of the outlet pipe. The flow rate has a great relationship with the fan speed. However, if the axial clearance is adjusted too large, a gas channel will be formed at the impeller end face and the bearing seat end face. The gas channel will make the pressurized air return through it
The suction port of the fan makes the fan continuously do quantitative useless work, which reduces the fan air volume and efficiency.
When the clearance of fan vibration is too small, the impeller end face will rub with the bearing seat end face. The unit will produce strong vibration due to friction between dynamic and static parts. Excessive vibration is easy to cause friction between the dynamic and static parts, which can lead to disastrous consequences. Friction occurs at the seal ring of the shaft, which will cause further increase of vibration caused by the thermal bending of the rotor, forming a vicious cycle and causing permanent bending of the rotor. However, vibration and shaft bending will cause bearing damage, gear damage, impeller damage, and even the whole Roots blower will be scrapped.
Text label: Roots blower
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