A rotor is a rotating body supported by bearings.When a disc or other object without its own rotating shaft is rigidly connected or attached, it can be regarded as a rotor.
according toISO StandardsThe rotating body supported by the bearing is called the rotor.The rotor is mostly the main rotation in power machinery and working machineryparts。
The rotating part of an electric motor or some rotating machines, such as a turbine.The rotor of the motor is generally composed of an iron core, slip ring, fan blade, etc. wrapped with coils.[1]
Motor, generatorgas turbineandTurbine compressorThe main components of high speed rotation in isodynamic machinery or working machinery.
rotor
The main rotor rotates at high speed, and the deflection deformation of the shaft occurs when its speed is close to the critical speed.Even mechanical damage caused by resonance.The natural frequency of the transverse vibration of the rotor is multi order, so its corresponding critical speed is also multi order.When the working speed of the rotor is lower than the first critical speed, it is called a rigid rotor, while when the working speed of the rotor is higher than the first critical speed, it is called a flexible rotor.
The operating speed of any type of rotor shall not be close to the critical speed.The critical speed of the rotor depends on its manufacturing materials, structural form, geometric dimensions, support characteristics and other factors.
working principle
Announce
edit
For example,induction motor The rotor, which is composed of a shaft iron core and a closed conductor embedded in the iron core, produces high-speed rotary motion driven by the rotating magnetic field generated by the stator winding.Both ends of rotor adoptRolling bearingIt is installed and fixed in the end cover of the motor housing.[2]
Because no matter what type of rotorCentrifugal inertial forceAnd affect the strength and mechanical efficiency of the rotor.Therefore, the rotors are properly balanced and the mass of each part is redistributed, so as to reduce the centrifugal inertia force generated in the process of rotation.
rotor[4]
When the unbalanced mass of the rotor is approximately distributed on the same plane perpendicular to the rotating shaft, such as the balance of a single disc cam, static balance can be achieved by increasing or removing the size and position of the balance weight, even if the center of gravity of the mass of each part of the rotor coincides with the rotating shaft.
When the unbalanced weight of the rotor is located in the parallel plane of the vertical rotation axis, the unbalanced weight will appear only after the rotor rotates. The elimination of this dynamic imbalance is mostly achieved by changing the weight and position of the balance weight, eliminating inertia force and inertia couple.Avoid vibration of rotor on elastic support.
Rotor classification
Announce
edit
Typical rotors areTurbomachineryRotorMotor rotorRotors of various pumps and turbine compressors.The rotor will deform greatly and cause resonance when rotating at some specific speed. The speed at which resonance occurs is called rotor speedcritical speed 。
In engineering, the rotor whose working speed is lower than the first critical speed is calledRigid rotorThe rotor whose speed is greater than the first critical speed is calledFlexible rotor。
Since the rotor rotates at high speed, it needs to be balanced.Static balance is mainly used forBalancing discToroidalinertia force。Rigid rotordynamic balanceGeneralBalancing machineTo balance the inertia force and inertia couple and eliminate the elasticity of the rotorsupportingVibration on.
The dynamic balance of flexible rotors is relatively complex, and there are mode balance method andInfluence coefficient methodTwo types.[3]
Common faults
Announce
edit
The rotor has frequent faults due to difficult commutation, high speed and various faults.Common faults include commutator damage, bearing damage, fan blade damage, brush wear, rotor winding burning, etc.
Commutator damaged
Common faults of the commutator are hole burning on the surface, flyout of the commutator, short circuit between the commutator and the commutator, out of round commutator, excessive wear of the commutator, protruding mica sheet, virtual connection between the commutator and the coil lead, etc.
For the faults such as burned holes on the surface of the commutator, flyout of the commutator, short circuit between the commutator and the commutator, and excessive wear of the commutator, the commutator should be replaced, and the rotor winding should also be replaced.
For the fault of out of round commutator, useHorizontal latheAfter processing, it can still be used.
If the commutating plate and coil cause false connection, the fault point of the false connection can be washed, riveted or welded as the case may be.If the fault point cannot be found, the commutator can only be replaced, and the rotor winding also needs to be replaced.
If the mica sheet of the commutator protrudes, the side with the teeth of the hacksaw blade can be polished thin, the mica will be lowered for a moment, and chamfering and grinding will be carried out.
Bearing damage
The commonly used bearing models of electric tools are 608, 629, 101, 102, 200, 201, etc.
rotor
The common faults of bearings are excessive clearance, bearing fragmentation, running of outer sleeve, running of inner sleeve, locking, etc.For faults such as excessive bearing clearance, bearing fragmentation, locking, etc., new bearings need to be replaced.For some running jackets and those with large gaps, thin iron sheets can be padded (for example, some iron beverage bottles can be used) or the casing can be replaced.For some gaps that are not too large, AB universal glue can be applied to solve the problem.For some inner sleeves, the method of punching pockmarks on the shaft can be used to solve the problem.
Blade damage
The fan blades are often broken, deformed and loose when they are in fault. The old parts can be removed or replaced with new ones.The deformed iron blades can also be corrected with pointed nose pliers.If the fan blade is loose from the shaft, it can also be glued with AB universal glue.
Brush wear
Generally, when the length of the brush is worn to 1/3 of the original length, it should be replaced.If the brush is too short, it is easy to burn the commutator and cause the rotor to be scrapped.The size of the electric brush is generally expressed as length × width × height. In addition to the same size, the brush shall be replaced with the same brand.Generally, two brushes shall be replaced at the same time.
