Differences in Dynamic Balancing Of Rigid And Flexible Rotors

Differences in Dynamic Balancing of Rigid and Flexible Rotors

Rotor dynamic balancing is the focus of the motor manufacturing process and key processes, for small specifications of low-speed motors, some motor manufacturers through the production process control, omitted the rotor balancing process, but for high speed, large specification products, dynamic balancing is listed as a key process of production and processing. Ms. Sen. friend of the company where the small L encountered a specification of a total of 10 high-voltage motors, production and processing process tracking links No abnormality was found in the production process tracking link, but the motor test showed vibration without exception; after repeated checking and argumentation, it was considered to be a problem of dynamic balancing of the flexible rotor.

Static balance is a calibration balance on a calibration surface of the rotor, after the correction of the remaining amount of unevenness to ensure that the rotor in the static state is in the permissible amount of unevenness of the specified range, static balance, also known as one-sided balance, static balance is the weight of the balance.

Dynamic balancing is in the rotor two calibration surface at the same time to correct the balance, after the correction of the remaining amount of unevenness to ensure that the rotor dynamic is in the permissible amount of unevenness of the specified range, dynamic balancing is also known as double-sided balancing, dynamic balancing is the balance of the moment of gravity.

If the rotor's operating speed is relatively low, the deflection of its axis of rotation is negligible, such a rotor is called a rigid rotor. On the contrary, with the increase of the unit capacity, the unit rotor axial size is getting bigger and bigger. Thin and long rotor, especially the rotor of the relatively high speed, flexural increase, for such a rotor, generally known as the flexible rotor.

For rotors whose operating speed is much lower than the critical speed, the deformation caused by the unbalance is very small. This kind of rotor can be treated as a rigid body, and dynamic balancing can be carried out at low speeds, which is called dynamic balancing of rigid rotors. In the dynamic balancing of rigid rotors, each micro-section of the unevenness of the centrifugal inertia force caused by the system can be simplified to any two selected cross-section, in these two surfaces for the corresponding correction can be completed dynamic balancing.

In fact, the use of rigid rotor balancing theory and method, the balance of the flexible rotor does not achieve the desired results. Ms. Sen. friend said 10 high-voltage motor rotor is a 2P motor, the rotor core is relatively short, and the shaft is relatively long and thin, is a typical flexible rotor.

Flexible rotors are deformed by the centrifugal force of an unbalanced mass, so-called elastic bending, and the degree of deformation varies with rotational speed.

Flexible rotor stiffness itself is poor, in high-speed rotation, its unbalanced centrifugal force generated by the rotor dynamic deflection will further generate additional centrifugal force, resulting in strong vibration of the rotor.

For the flexible rotor, should be in the full operating speed conditions to achieve smooth operation, so that the flexible rotor should be balanced in the full-speed conditions and try to close to the operating speed. As with rigid rotors, the vibration caused by the unbalance of a flexure rotor is positively related to the speed. The rated speed of most dynamic balancing equipment is limited by the equipment itself. In order to ensure that the rotor is balanced to meet the needs of the market, there are dynamic balancing equipments for high-speed and large-size rotors, which can undertake high-speed dynamic balancing of rotors of rotating machinery, overspeed tests, and experimental research on the strength and vibration of new products. The rotor types include: turbine rotor, generator rotor, compressor rotor, fan rotor, etc. The rotor speed is up to 15,000 rpm. The maximum speed is up to 15000r/min.