Diaphragm couplingThe problems in the maintenance and installation are as follows:
1. Regarding the alignment standard.At present, the alignment standards are only the requirements for radial runout and end runout. For diaphragm couplings, the requirements of "General Specification for Construction and Acceptance of Mechanical Equipment Installation Engineering" GB50231-1988, radial ≤0.15mm, end runout ≤0.1 mm, the Ministry of Chemical Industry standard is also equivalent, but this standard does not apply to all diaphragm couplings during normal maintenance and installation.
2. The coupling diaphragm is mainly subjected to 4 kinds of forces.
(1) The film stress produced by torque, the force produced by one side of the torque, is evenly distributed on the four spaced bolt holes. On the 4/1 diaphragm taken, the force acts on the middle bolt hole in the circumferential direction In the middle of one side, the radial displacement and the axial displacement are fixed.
(2) Centrifugal stress produced by centrifugal inertial force.The centrifugal inertial force of high-speed machinery is very important in the stress calculation of the structure. The centrifugal inertial force can be loaded according to the radial unit body force f=2rp (2πn/60), and the direction is radially outward. In the formula, n is the speed ,r is the radius, p is the density.Fix the radial displacement, circumferential displacement and axial displacement of the middle bolt hole without other surrounding loads.
(3) Bending stress caused by axial installation error.Due to the actual installation error in the axial direction, the diaphragm is bent and deformed along the axial direction.The displacement is loaded in the axial direction of the middle bolt hole, and the radial displacement and the axial displacement are fixed.
(4) Bending stress (periodical stress) caused by angular installation error.Due to the actual installation error in the axial angular direction, the diaphragm is periodically bent and deformed along the axial direction, and it is the main factor that determines the fatigue life of the diaphragm.
3. The distance deviation of the coupling end face.
The requirement for the distance deviation of the end face of the diaphragm coupling is based on the formula of the additional stress generated by the relative displacement of the two shafts.In the case of axial installation distance deviation, when the coupling bolts are tightened, the diaphragm will be stressed (assuming 6 coupling bolts).When there is deviation between the angle and the radial direction, the force of the diaphragm will generally exist at the same time during installation, which will result in a superposition of forces.Coupled with the axial displacement generated during the operation of the equipment, it may accelerate the damage of the diaphragm.The thickness of the corresponding large cover gasket after tightening and compression is only 3.5mm. Therefore, it is judged that because the gasket is thicker, uneven compression during the tightening process causes the bonding surface to tilt and produces out-of-concentric deviations.