Gap of Roots blower and its adjustment steps
The maintenance difficulty of Roots blower is the adjustment of clearance. Proper clearance should be maintained between the two impellers and between the impeller and the casing and the wall plates at both ends to ensure the normal operation of Roots blower. If the gap of Roots blower is too large, the gas leakage will be large and the performance of the fan will be very high. If the gap is too small, the thermal expansion of Roots blower housing and impeller will be different. In the process of operation, equipment failure will occur. Next, Hongguang Machinery introduces the clearance data of various parts of Roots blower
1： Clearance between rotor and housing
The original radial clearance value of the rolling bearing of Roots blower is determined according to the accuracy of the bearing. The inner diameter of 0026u is used for bearings. 50-8 phi; 200 mm, with radial clearance between 0.03 and 0.1 mm. In order to avoid friction between the rotor and the housing, the clearance is usually between 0.25 and 0.7 mm, or adjusted according to the instructions.
2： Clearance between rotor and wall panel
The impeller of blower is installed at one end with self-aligning bearing, and the outer end is roller bearing without rim. Therefore, the axial clearance between impeller and front wall plate and rear wall plate is basically achieved by adjusting the axial position of double row self-aligning bearing. During installation, the gland and bushing of inner ring and outer ring of double row self-aligning bearing must be tightened. The wear of double row self-aligning bearing makes the impeller move axially. In order to prevent the rotor from rubbing the front and rear panels, the clearance is usually determined by calculation.
3： Rotor outer diameter clearance
The outer surface of the rotor is an involute surface, so it is similar to an involute gear in operation. This is why it is possible to adjust the gap value of all meshing common normals of both rotors to the same value.
When the rotor is in the 45 degree position, the meshing point just falls on the middle point (node) of the connection between the centers of the two rotor shafts with the horizontal line. Here, the wear is very small, theoretically, the joint is not worn. The clearance value should be measured when the rotor is at 45 degrees: the rotor has 4 pairs of meshing surfaces, so 4 points should be measured. Let's refer to the pictures to introduce the steps of gap adjustment.
A. adjust the clearance of impeller.
Loosen the "key 18" lock nut and adjust the installation angle between the two gears to achieve the effect of adjusting the clearance. After adjusting the clearance, tighten the lock nut and secure it with the "part No. 17" tab washer. Contour clearance adjustment shall be made by 360 ° rotation. When the rotation angle is 60 °, the meshing clearance of 1 / 6 impeller profile can only be measured.
B. adjust the clearance between impeller and wall plate.
Firstly, the difference between the axial length of Roots blower shell and impeller should be equal to the sum of the axial clearance δ 3 at the driving end and δ 4 at the tooth end. Otherwise, the length and tolerance of wall plate or impeller should be adjusted. For the values of δ 3 and δ 4 that do not meet the requirements, the length and tolerance of "No.7" drive seal bushing and "No.8" tooth end seal bushing can be changed to adjust δ 3 and δ 4 to reach the required clearance range. The difficult task of adjusting the axial clearance between the front and rear wall plates should be careful. It is recommended to contact roots blower manufacturer for maintenance!
Conclusion: the reasonable adjustment of impeller static clearance should be determined by the calculation of shaft torsion deformation, so as to make the dynamic clearance value after fan operation. If necessary, the following limit adjustment method can also be used; under the premise of ensuring the continuous flow of the car, the gap value should be adjusted as much as possible.
Roots blower clearance and clearance adjustment steps: http://theoxfordjazz.com/xw/73.html
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