In fact, the size and position of the disequilibrium point of any motor rotor that needs to be balanced are unknown and cannot be calculated. Only the dynamic balance testing machine can be used, that is, the size and phase of the balance mass that should be weighted or reduced on the two planes during the operation can be measured.

The precision of dynamic balancing machine and rotor allowed dynamic balancing precision are two different concepts, can not be confused.Dynamic balancing machine is a kind of mechatronics detection equipment, its mechanical part is composed of the base, swing frame (including roller frame), transmission device and sensors and other parts, that is, when the rotor is rotating on the swing frame, the small amplitude of the swing frame, through the sensor will be mechanical signal to the electrical test box process called unbalance test.The accuracy of the dynamic balancing machine is the mechanical part of the quality of each link accumulatively confirmed.It includes the processing error of the parts, the concentricity of the assembly, the error of the universal joint and the driving wheel in the transmission device, the tolerance gap matching error of the joint sleeve, the sensitivity and linearity matching of the two sensors and other influencing factors.Therefore, in order to finally obtain the precise unbalance value and the corresponding Angle position, it is necessary to input the mechanical signal into the electrical test box, and then obtain it through the calculation of each link in the electrical test box, and delete and filter the useless signal.The precision of dynamic balancing machine is determined by the quality of components, software and circuit.At present, domestic enterprises are in accordance with the international standard iso2953:1999 international standards and industry standards for product delivery inspection.For the general balancing machine check can be in accordance with the national standard "general horizontal balancing machine check method" (gb4201-84) and "vertical balancing machine check method" (gb7622-87) as the basis of the rotor check.

The important factor of the quality of the motor and machinery dynamic balance is the speed, and the factors affecting the speed can be divided into the following three categories:

The first is the rotor speed, which is affected by factors such as mass, moment of inertia, inch method, allowable residual unbalance, rotor characteristics, rigidity, winding, etc.

The second kind is to balance the machine speed, the factors that affect it include working range supporting form, driving form, driving power and measuring system.

The third is the overall speed, which is affected by the factors of preparation, cycle time, necessary protection, calibration, energy consumption, etc.

Although rotor unbalance is a very complex work, but through understanding the electronic principle of dynamic balancing machine, process design and improvement from several directions, finally to improve product quality, prolong the life of the rotor.

FIG. 1 schematic diagram of electronic dynamic balance

The first is the choice of measurement mode.Generally different balance machine measurement mode is different, the force of the application of "hard support" balance machine, and the displacement of the application of "soft support" balance machine.Therefore, from the perspective of technology, the analysis of the driving system has become the primary factor in the design.At present, the dynamic balancing machine drive system has belt drive system, compressed air drive system, open electromagnetic drive system, self-drive system, etc.Manufacturing enterprises can choose driving system according to their own needs and costs.(see figure 5 below)

At present, manufacturing enterprises can choose dynamic balance driving system according to operating efficiency, stability, activity and other factors.

The tangent type of belt drive system is often used.The reason is simple design, easy to take and put products, equipment maintenance and belt replacement, suitable for standardized production.The upper belt drive system and the lower belt drive system can also be selected according to the production requirements.Although the two terms are more stable, the unbalance is affected by the friction between the fixtures.At the same time, operators are not easy to operate.Below is the belt drive system mode simulation graphics.

FIG. 2 schematic diagram of special drive system

Figure 3 belt drive system mode

The second technological concern is the choice of swing frame and support seat.The more stable the external factors such as drive system, swing frame and support seat are, the higher the measurement precision of the balance quantity affecting the automobile motor will be.Figure (7) is the design pattern of swing frame and support seat that we often design and apply.Two and three of them are the best models.

FIG. 4 design mode of swing frame and support seat

The third item is from the measurement signal analysis, through the Fourier analysis method the vibration sensor signal waveform filter input to the measurement system, carries on the determination.The more thoroughly the clutter is filtered, the more accurate the balance measurement data will be.(see figure 8 below) therefore, when measuring the dynamic balance of the motor rotor, the temperature of the device, the mechanical stability, the interference of the electronic pulse generated by the filter switch and the contactor, as well as the occurrence frequency and time law of errors should be confirmed first.That is, the initial state of the device.

The fourth item from the measurement system standard parts correction analysis.The precision of the measurement value of the dynamic balancing machine depends on the accuracy of the calibration of the standard parts in the early stage of the dynamic balancing machine.The basic practice of this standard is to mark two horizontal nail holes on the same surface of the iron-core rotor.Note that the surface must be made into the horizontal plane of the Angle sensor, and then correct the rotor to be below 0.010g for both left and right dynamic balance, the smaller the better.

FIG. 5 schematic diagram of filtered vibration sensor signal

Finally, the standard nail weight is selected to correct the speed, unbalance and Angle of the dynamic balancing machine.The higher the accuracy of the standard part, the higher the correction efficiency of the rotor.

Figure 6 criteria see this example

See the standard as a key product for future equipment accuracy confirmation and calibration, long-term application.So pay special attention to its accuracy and state.

Figure 7 manufacturer and user requirements for unbalance criteria

The vibration and noise reduction of micromotor have been paid more and more attention by motor manufacturing technicians.The mass distribution of the rotor is unevenly and asymmetrically distributed on its axis.Affect the performance of generator, shorten its service life.Therefore, the micromotor manufacturing industry and design all hope to accurately judge and correct the existing motor design.Due to the complexity of dynamic balancing operation and calculation and too many factors, many dynamic balancing mechanism manufacturers improve the mechanical sensor output signal amplification driver system.The dynamic balancing machine design is convenient and accurate to meet all kinds of micro-motor 100% for measurement and correction, to improve product quality, extend the life of the product.