How to align the coupling correctly?

   CouplingDue to various reasons, the center of mass or the inertial principal axis does not coincide with the axis of rotation, and the phenomenon of unbalanced centrifugal inertial force, centrifugal inertial couple force and dynamic deflection (vibration shape) will occur during operation, which is called the unbalanced phenomenon of the rotor. This kind of unbalance phenomenon will inevitably cause the vibration of the shaft system, which will affect the normal operation and service life of the machine, so it should be paid attention to.The degree of unbalance (unbalance U) is usually expressed by the product mr of the mass m of the rotor and the distance r from the center of mass to the axis of rotation of the rotor, which is called the product of mass diameter.It is also expressed by the product of mass diameter per unit mass, called the eccentricity e (not geometrically eccentric.) The product of mass diameter mr is a relative quantity related to the mass of the rotor, while the eccentricity e is a value that has nothing to do with the mass of the rotor.的量。 The amount.The former is relatively intuitive, and is often used for specific balancing operations of a given rotor. The latter is used to measure the pros and cons of the rotor balance or to detect the balance accuracy. The balance grade standard of the coupling is evaluated by e.For a flexible rotor, use the mode eccentricity (the nth mode) en=Un/mn, and Un and mn are the nth mode and the first mode quality respectively.
In order to correct or reduce the unbalance of the coupling, the appropriate balance level should be selected according to the needs, and after the product is manufactured and installed on the machine, on the balance (correction) plane designated by the coupling, increase or decrease Appropriate quality method to achieve the balance level requirements.This process is called balance correction, or balance for short.
The alignment of the coupling is divided into four steps.Now let's talk more carefully.
　　1. Radial alignment of the coupling
　　CouplingWhen aligning, the vertical direction should be adjusted.The thickness of the front and rear foot pads can be calculated from the three-point detection data, and the offset of the two shafts can be detected.The diameter of the outer edge of the movable end coupling plus the distance from the outer edge of the coupling to the center of the axial dial gauge rod hole; the distance from the end face of the movable end coupling to the center of the front foot bolt of the movable end; the front of the movable end, The distance from the center of the rear foot bolt.From the above data, the thickness of the front and rear foot pads can be known.If the motor is higher than the fixed end, shims should be reduced; if the motor is lower than the fixed end, shims should be added.
　　After adjusting the vertical direction, the detection data of each point has changed, it should be reset at the 1 point position, and the data of 2 and 3 points should be measured again.After adjustment, just check whether the sum is within the allowable error range.
　　2,CouplingPrinciple alignment
　　The projection of the circle of the movable end face of the motor on the end face of the fixed end is approximately regarded as a perfect circle, because the distance from the center of the movable end to the end face of the fixed end does not change.If you want to meet at the same time, the axis of the movable end and the axis of the fixed end are on the same line, which is just an ideal alignment state.In actual alignment, set the allowable error first, and when the error generated during alignment is within the allowable error range, alignment ends.In many occasions, the lower detection point of the pump cannot be detected, and the alignment work cannot be performed.
　　3. Steps for correcting the three-point table method
　　(1) Fix the magnetic fixed seat, the measuring rod and the dial indicator on the couplings of the fixed end and the movable end respectively; (2) Turn the shaft to the 1 o'clock position, and clear the two dial indicators respectively; (3) Then turn the shaft to the 2 o'clock position and read the data; (4) Turn the shaft to the 3 o'clock position and read the data; (5) Calculate separately (6) Loosen the front and rear bolts of the motor, Pad the rear feet with thick gaskets, move the motor, try to make the two couplings close, and then tighten the front and rear bolts of the motor, clear the two dial gauge at 1 o'clock, and read at the 2 and 3 o'clock positions. The data is compared with the set allowable error value. If the accuracy requirements are not met, repeat the above steps 2-6; (7) After step 6 is satisfied, loosen the front and rear bolts of the motor slightly, and keep the dial indicator at 3 o’clock Tap the front and rear feet of the movable end, and the middle of the movable end with a copper rod, and perform horizontal alignment until it is within the allowable error range; (8) After step 7 is satisfied, tighten the front and rear foot bolts of the movable end , The alignment is over.
　　4. Axial alignment of the coupling
　　Alignment in the horizontal direction does not need to calculate the amount of front and rear feet of the movable end, clear the axial and radial dial gauges at 1 o'clock, read the readings of the axial and radial dial gauges at 3 o'clock, and tap with a copper rod The movable end can adjust the axis.Observe the reading of the axial dial gauge first, tap the front and rear feet of the movable end with a copper rod, and adjust the axial reading at 3 o'clock to half of the original.Observe the reading of the radial dial gauge again, tap the middle of the movable end with a copper rod, and adjust the radial reading at 3 o'clock to half of the original.This requires repeated adjustments.The adjustment result should make the sum within the allowable error range.