Online Dynamic Balance Research Articles

Development of single measuring point overall balancing method based on multi-cylinder dynamic balance detection system

The combine harvester with multi-cylinder has a wide application in improving the operation efficiency. Therefore, as an important process in combine harvester, threshing operated by multi-cylinder usually makes the working structures suffer hit from the blockage of stones or materials. Consequently, the cylinders fail to guarantee the original balance. Several studies have been performed in this area, based on the dynamic balance method and vibration signal processing. However, most of them are not efficient for multi-cylinder. This study aims at developing an online dynamic balance detection system for multi-cylinder in combine harvester, in order to enhance the efficiency and accuracy of online dynamic balance detection. A multi-cylinder test rig is developed, and unbalanced vibration experiments under different working conditions are performed. The results show that the different measuring positions have different sensitivities to unbalanced mass. The vibrations will be transmitted through the frame, and coupled with each other. Under the multi-cylinder rotation, the vibration has strong randomness and poor convergence. For this purpose, the single measuring point overall balancing method is proposed. An adaptive multiple filter algorithm relying on the LabVIEW platform, is also proposed. Through phase relation between cylinders, the single measuring point overall balancing algorithm is developed. The comparison experimental results show that the proposed algorithm is more robust under the multi-cylinder rotation. The proposed method simultaneously installs sensors on the bearing seat of No. 1 tangential cylinder and balance 3 cylinders. The traditional method balance 3 cylinders separately change the sensor position. The effect of the proposed method is almost 76%, while that of the traditional balance method is almost 66%. For the multi-cylinder system, the single measuring point overall balancing method can efficiently improve the balance effect by 10%. Finally, it can be deduced from the experiment on the combine harvester that the accuracy of the proposed method reaches G3.9.

Optimization method based on genetic algorithm for the mass compensation of the rotor on-line dynamic balance system

Abstract The rotor is the key component of the rotary drilling rig, it can realize the rotation and feed movement of the drill. the rotor unit of the rotary drilling rig should take on-line dynamic. Because unbalanced faults would lead to vibration. In order to further improve the pricision of on-line dynamic balance, an optimization strategy based on Genetic Algorithm for the mass compensation of the rotor on-line dynamic balancing system is proposed. A mass compensation optimization model is established. By the way of taking the phase of counterweight movement as the optimization variable. At the same time,taking the residual stress under dynamic balance as the optimization objective. According to the principle of Genetic Algorithm, the movement phase of the counterweight can be calculated when the residual force reaches the minimum value. By performing simulation analysis, the residual force can be calculated under different rotating speeds and different amount of unbalance, the residual force after optimizing balance can be reduced greatly. The simulation results showed that the residual force of the rotor after optimizing balance can decrease by 95.74% on average. Therefore, an optimization strategy based on Genetic Algorithm for the mass compensation of the rotor can effectively improve dynamic balance precision and operating performance of rotary drilling rig.

Study on Moving Strategy of Internal Mechanical On-Line Balancing System

Mechanical balancing system driven by the motor can cause wrong adjustment and long balancing time in the controlling process, which will result in lower accuracy of rotation. In order to solve this problem and achieve more efficient online dynamic balance, the optimal moving path of the built-in mass block of balancing device can be determined by us. Four kinds of moving paths for mass block are designed by using for balancing to make experimental verification of spindle dynamic balance movement. By comparing experimental results of balance accuracy and balance efficiency, the optimal dynamic balancing strategy is determined. The results show that the designed moving strategy is reasonable, and the moving optimized path can carry out more accurate control precision and shorter adjustment time to achieve the expected effect. The better control strategy of dynamic balance lays the foundation for the high-precision operation of the spindle system.

Optimal design and experiment study of the double spherical rotor of the MSCSG.

The magnetically suspended control and sense gyroscope (MSCSG) integrates spacecraft attitude measurement and control function; this paper proposes a double spherical rotor (DSR) for MSCSG. The DSR realizes the five degrees of freedom (DOFs) full active control and full channel magnetic path decoupling by the following design: the spherical axial/radial reluctance magnetic bearings are adopted to control the 3DOFs translation of rotor in the range of double spherical envelope, Lorentz force magnetic bearing (LFMB) is used to precisely drive the 2DOFs universal deflection of rotor. The optimization model is established based on the structural mechanical analysis, taking the deviation between rotor centroid and shape center as the optimization objective, choosing the first order resonance frequency, maximum equivalent stress, rigid body displacement, polar moment of inertia and inertia ratio as constraints. Then the DSR is optimized and simulated by the finite element, the MSCSG principle prototype based on DSR is successfully developed, the online dynamic balance experiment and modal test of the DSR are conducted, where the vibration amount of the DSR decreases from 20 μm before the experiment to 0.14 μm after the experiment, which decreases by 99.3%, the first test modal is 2881 Hz which is 5% different from the finite element simulation value of 3034 Hz. The results show that the DSR has the good mechanical properties and magnetic circuit decoupling characteristics.

Static and dynamic characteristics analysis of self-balancing motorized spindle

In order to effectively suppress the vibration of motorized spindle caused by unbalance fault, realize online dynamic balance control of motorized spindle unit. A self-balancing motorized spindle with dynamic balancing device is designed and the finite element analysis of self-balancing motorized spindle is carried out. The static analysis is carried out, and the static deformation diagram of spindle is obtained after constraint and load are applied. Then modal analysis and harmonic response analysis are carried out, and the first six natural frequencies, mode shapes and displacement frequency curves of spindle are obtained. The results show that: The deformation of motorized spindle is small and rigidity of spindle meets design requirements: Within the working speed range, the spindle will not resonate and work stably and reliably. The rationality and reliability of structure design of self-balancing motorized spindle are verified.

Optimization and Experiment of Mass Compensation Strategy for Built-In Mechanical On-Line Dynamic Balancing System

In order to solve the problem of low precision and efficiency in the balancing process due to the movement of balance counterweights in a built-in mechanical on-line dynamic balance system, an optimization strategy for the mass compensation of the mechanical on-line dynamic balancing system is proposed, and a mass compensation optimization model is established. The optimization model takes the phase of counterweight movement as the optimization variable and the residual stress under dynamic balance as the optimization objective. Through the optimization model, the movement phase of the counterweight can be calculated, and the counterweight can be moved to a balanced position that significantly reduces the degree of unbalance. An experiment platform was built to carry out comparison experiments under different rotating speeds and unbalance levels. By comparing the residual stress, amplitude, and dynamic balancing time of the spindle before and after the balance, the accuracy of the phase of the counterweight that is calculated by the optimization model is verified. The optimized dynamic balance compensation strategy and the unoptimized were compared by experiments at different rotating speeds. The experimental results showed that, compared to the unoptimized balance, the amplitude of the spindle after optimizing balance with a dynamic balancing device can decrease by 30.39% on average, with its maximum amplitude decreasing by up 50.18%, and the balancing time can decrease by 31.72% on average, with its maximum balancing time decreasing by up to 43.86%. The research results showed that an optimization strategy can effectively improve dynamic balance efficiency and greatly reduce vibration amplitude, which provides the necessary theoretical basis for improving the running precision of the spindle system.

A new dynamic balancing method of spindle based on the identification energy transfer coefficient

A new vector matching balance method (VMBM) based on the identification of energy transfer coefficient of spindle rotor system (ETCSRS) is proposed in this paper. This method only needs to extract the original vibration signal of the spindle to compute the spindle rotor system unbalanced vector, and the calculation accuracy depends on the identification precision of ETCSRS. The initial parameters of bearings were calculated by applying Newton-Raphson algorithm based on the quasi-static mechanics analysis of rolling bearings. Through establishing the FEA model of spindle, the structural parameters of the rotor shaft system are obtained and modified by modal correction method. First, the principle of VMBM is verified on a Bentley rotor test bench at different rotating speeds. Second, the verification experiment of VMBM on a high-speed spindle is carried out. Furthermore, the VMBM has a better performance than the influence coefficient method (ICM). The method proposed in this paper is very suitable for on-line dynamic balancing, since it greatly improves the balance efficiency.

Study on vibration extraction and control characteristics of the high speed spindle online dynamic

In order to solve the mechanical spindle low processing accuracy and precision elements problems which were caused by high speed spindle noise and vibration, a robust and reliable vibration extraction and control scheme of mechanical spindle was proposed. Based on the electromagnetic balancing system and by applying LabV1EW visual instrument, high speed spindle noise reduction and vibration signals filtering were pre- processed and vibration signals sampling, quantization, interception were post-processed. Base frequency vibration signals amplitude and phase were extracted by using different signal extraction methods. Through experiment verification and comparative analysis, the optimal vibration signal amplitude and phase extraction method was selected. By using the influence coefficient method, the influential factors including spindle speed, trial weights magnitude and phase were analysed. The high speed spindle unbalance was calculated and compensated. The high speed spindle electromagnetic balancing device block was controlled accurately. Experimental results showed that the vibration amplitude of the mechanical spindle was obviously reduced and the balance efficiency was greatly improved. The influence coefficient method and the electromagnetic balancing system took an active role in the process of dynamic balancing regulation. Such achievements enriched online dynamic balancing theory and promoted the relevant control technique developments.

Online Dynamic Balance Technology for High Speed Spindle Based on Gain Parameter Adaption and Scheduling Control

Unbalance vibration is one of the main vibration forms of a high speed machine tool spindle. The overlarge unbalance vibration will have some adverse effects on the working life of the spindle system and the surface quality of the work-piece. In order to reduce the unbalance of a high speed spindle system, a pneumatic online dynamic balance device and its control system are presented in the paper. To improve the balance accuracy and adaptation of the balance system, the gain parameter adaption and scheduling control method are proposed first, and then the different balance effects of the influence coefficient method and the gain scheduling control method are compared through many dynamic balance experiments of the high speed spindle. The experimental results indicate that the gain parameters can be changed timely according to the transformation of the speed and kinetic parameters of the spindle system. The balance accuracy can be improved for a high speed spindle with time-varying characteristics, based on the adaptive gain scheduling control method.

Investigation on a No Trial Weight Spray Online Dynamic Balancer

In order to suppress the spindle vibration with high efficiency and high precision, a no without trial weight spray online balance method is proposed in this paper. By analyzing the relationship between the unbalanced excitation and the unbalanced response of the spindle, the relationship between the dynamic influence coefficient and the system model is studied. A high‐speed spindle finite element analysis model was established, and the dynamic influence coefficient matrix was identified. A no trial weight spray online dynamic balancing system was developed, which has the advantages of without trial weight and high‐precision loading. A new type of integrated balancing terminal that was formed using 3D printing technology was first proposed by our research group, and its advantages in various aspects are significantly higher than traditional assembly balanced terminals. The experimental verification of the without trial weight spray online dynamic balancing system was performed on a high‐speed spindle test stand. Experiments show that the no trial weight spray online balancing method proposed in this paper can achieve high‐efficiency and high‐precision vibration suppression, greatly reducing balance time and cost of the spindle. At the same time, the online balance test also verified the reliability of the integrated balanced terminal.

Online Dynamic Balance Detection Method of High Speed Motorized Spindle Based on LabVIEW

Aiming at the dynamic unbalance problem of high speed motorized spindle, an online dynamic balance detection method based on Fourier transform, polynomial curve fitting and Hooke's law is proposed, at the same time, based on virtual instrument LabVIEW software platform, programming deal with the vibration spectrum image of the motorized spindle. Combined with the detection method, output signal of the size, displacement and vector direction of unbalance force of the motorized spindle are obtained, the output signal would be transmit to dynamic balancing device to complete regulation of high speed motorized spindle online dynamic balance and achieve the real-time monitoring, analysis and timely adjustment of dynamic balance of high speed motorized spindle by using the programming of virtual instrument. We verified detection method by the experiment of online dynamic balance adjustment of the motorized spindle. Detection method of dynamic balance of motorized spindle based on LabVIEW can intuitively test vibration characteristics, the accurate detection of online dynamic balance is helpful to improve the rotation precision of the high speed spindle and realize high quality parts processing.Key words: Motorized spindle; the dynamic balance; Online detection; LabVIEW

Development and Experimental Study of the Online Dynamic Balance System for Grinding Machine

The vibration of grinding wheel spindle will significantly reduce the machining quality and machining accuracy of precision grinding. In order to suppress the grinding wheel rotor vibration effectively, the Spray-Typed online dynamic balance system for specific grinding wheel spindle was designed composed of terminal balance, hydraulic system and control system. To achieve the amount of spindle unbalance accurate extraction and liquid volume control, using hydraulic system to achieve the balance of the terminal of the liquid loading and using high-performance DSP chip as a control method. A segmented spindle online dynamic balance method , combining the advantages of influence coefficient method and coordinate rotation optimization method was proposed. The method can fast approaching the goal of balancing and meet the local precise adjustment of the balance weight. At last, the online dynamic balance experiment of grinding wheel spindle is carried out in the industrial field, the grinding spindle vibration displacement amplitude decreased from 17.8 to 7.7 before and after balance, fall by as much as 55%, which verifies the validity and feasibility of the system.

Analysis on High-Speed Spindle Online Dynamic Balancing Regulation Characteristics

In order to solve the spindle vibration problem which is mainly caused by the mass unbalance, the single-plane influence coefficient balancing technique was applied into the experimental study. The unbalance elimination could be done through correction weight through before adding trial weight. The coefficient magnitude, the balance weight magnitude and other parameters could be available by extracting vibration signals and measuring vibration phases. The dynamic balance effect comparison has been done under different working rotations. Results indicate that the spindle mechanical vibration decreased by 87.04%, the balancing precision also improved a lot. Such achievements would surly hold an important meaning in reducing noise, improving the equipment service life and ensuring the safely working machine.The method provides regulation strategies for the online dynamic balancing control technique. Key words:single-plane influence coefficient balancing technique; regulation strategy; mechanical vibration

Recent Researches and Patents on Dynamic Balancing Methods and Devices for Rotor System

Background: With the development of high-speed and high-precision rotating machinery, the rotor usually needs to work at very high speeds and the huge unbalancing vibration of rotor may be caused by a tiny unbalancing mass. To reduce the unbalance of rotor, a suitable dynamic balancing method should be designed for different rotor systems. In this article, various patents have been discussed. Objective: The typical dynamic balancing methods and technologies are summarized and analyzed so as to provide some references for dynamic balancing design and application. Method: To make it easier to design the proper balancing measure for actual rotating mechanical system, the dynamic balancing methods for rotor are classified as workpiece dynamic balance, assembling dynamic balance, field dynamic balance and online dynamic balance according to the balancing time of rotor. Results: The principle of all kinds of dynamic balancing method is given firstly, and then advantages, disadvantages and future developments about each balancing method are reviewed in the paper. Conclusion: Corresponding to these balancing methods, the online dynamic balancing method is recommended. Keywords: Device, dynamic balance, method, patent, research, rotor.

Design of an active dynamic balancing head for rotor and its balancing error analysis

The unbalancing vibration monitoring and control of rotating machinery is an important engineering problem. In order to correct the unbalance of rotor system online, an active dynamic balancing head is designed based on the ratchet-pawl mechanism and pneumatic technology. The inner mass distribution state of balancing head can be changed to correct the unbalance when the rotor system is working in unbalancing condition. The mechanical principle and pneumatic control system of the balancing head are introduced in the paper. Based on a double-face online dynamic balancing experiment system, the balancing effect of the balancing head has been proved by many experiments. In order to improve the dynamic balancing accuracy of the balancing head in the practical application, the possible influencing factors of dynamic balancing accuracy are analyzed in the paper.

A new double-face online dynamic balance device and its control system for high speed machine tool spindle

Dynamic balance technology is one of the basic questions that must be considered during the high speed, high-precision machine tool’s design and production course, and its function has a great impact on the working performance, efficiency and life of the machine tool. A new double-face online dynamic balance device with a pneumatic driving system is designed in the paper. Compared with similar balance devices, the dynamic balance device has many advantages: the mechanism structure is simple, the body dimension (the axial dimension in particular) is small, the practical application in the machine tool is easy to realize etc. In order to accurately separate the unbalance vibration component from the vibration measuring signal, the least square algorithm is adopted to fit the fundamental frequency signal. The method has a theoretical advantage compared with the traditional fast Fourier transform algorithm. Based on the influence coefficient principle, the implementation steps of the double-face online dynamic balance are designed. Based on these steps, the location experiments are done to test the position correcting error of the balance discs, the test weight experiments are done to estimate the influence coefficient, and the balance correction experiments are done to examine the online dynamic balance effect. The experimental results indicate that the online dynamic balance device and its control system have the advantage that the system is stable and reliable, the location of the balance disc is accurate and the dynamic balance precision is high.

Research on Gain Scheduling Control of Online Dynamic Balance for Flexible Spindle

The gain scheduling control is widely used in the system, whose dynamics parameters change with the operating conditions. In order to adapt the dynamic parameter variety of the high-speed and flexible spindle, the gain scheduling control method is applied to control the unbalance vectors of the correcting faces. The algorithm principle of gain scheduling control and its control method are given in the paper. The flexible spindle experiment system is designed to test the dynamic balance effect of gain scheduling control method. The experiment result indicates that the unbalance vectors of the correcting faces tend to be stable and close to the actual demand based on the gain scheduling control, and the residual unbalance vibration of the two monitoring points tend to be average and small.

Vibration extraction method research for on-line dynamic mass balance

Vibration extraction method research for on-line dynamic mass balance

Research on Double-Face Online Dynamic Balance Technology of Machine Tool Spindle

Based the principle of online dynamic balance device with balancing disks, the design method of embedded double-face online dynamic device was proposed. Balancing disks could be disengaged from the spindle by Hydraulic system, and the rotating speed of the disengaged disk was kept steady and under the speed of the spindle by friction torque. The systems of signal acquisition, signal analysis and control, hydraulic pressure were designed. The feasibility was proved and analyzed by examples.