Dynamic Balancing Machine Research Articles

Optimization Analysis of the Wheel Hub Dynamic Balancing Machine Based on Particle Swarm Optimization

The vibration supporting rod of a wheel hub dynamic balancing machine is affected by the alternating dynamic load, and its vibration characteristics have a direct impact on the accuracy of measurements. To solve this problem, first, a particle swarm optimization algorithm (PSO) algorithm is proposed to optimize the dynamic stiffness of the vibration supporting rod. According to the actual material selection, the creep risk of the rod is reduced. Second, three schemes for improving the structure of hub balancing machines are put forward and compared. The displacement response and stress response of scheme A are increased by 30% and 20%, respectively, over those of the original equipment. The displacement response and stress response of scheme C are increased by 31% and 22%, respectively, which is a significant improvement. Schemes A and C are acceptable, but a strong first-mode response remains due to assembly variation.

Vibration signal denoising method based on CEEMDAN and its application in brake disc unbalance detection

The research objective is the application of the modal decomposition methods in dynamic balancing machine detection. This paper analyzes the problem of feature extraction of dynamic unbalanced signals by using complementary EEMD with adaptive noise (CEEMDAN). CEEMDAN was introduced to decompose the original unbalanced signal. The orthogonal coefficient method, wavelet soft threshold method, and autocorrelation function (ACF) was introduced to remove the irrelevant intrinsic mode functions (IMFs). Moreover, we compare and analyze these methods through simulation and experiments. Simulation results demonstrate that the CEEMDAN method greatly reduces the reconstruction error. The feasibility of the proposed method has been verified experimentally, the real machine signal is sampled and the actual imbalance information is extracted for comparison, which proves the superiority of CEEMDAN over EMD and EEMD in practical applications.

Research on the Weight Removing Model and Control Method for the Unbalance Vector of Thin Disc Workpiece

Aiming at the structuring characteristics of thin disc workpiece, we propose the weight removing model and control methods to reduce the mass unbalance vector. Based on the material removing and correcting principle for unbalance workpiece, the weight removing model of drilling and reaming hole way and internal and external arc milling is discussed. The iterative control method with variable weight removing rate is proposed to reduce the weight removing material of the first-time correction and improve the ultimate correcting accuracy. The online measuring and correcting feasibility for unbalance workpiece is verified by experimental way. The advantages of the proposed iterative control method are discussed by simulation analysis. The research results can be used for the online correction of the unbalance disc workpiece on the NC machine tools or automatic dynamic balancing machine.

Development of Alternative Method of High-Speed Balance for the Turbine Rotor

This paper presents a computational evaluation of the alternative method of high-speed balance for a turbine rotor. The most important characteristic of this method is to balance the turbine rotor with removing the unbalance of the rigid and bending mode component. In the 1st step of this method, “full” balancing is conducted to the shafting itself before attaching mass bodies including blades. The method obtains two advantages from this step: the enlargement of the turbine rotor for same dynamic balancing machine, and the improvement of the balance effect with consideration on the flexible option of the modified plane. After the 1st step, the balancing is done with attachment of blading parts at low speed only to remove the unbalance of the rigid mode component. The 1-D CAE was done to evaluate this method and concluded that it could be decrease the vibration displacement by removing the unbalance component. The reduction effect of this method is about 1/10-1/15 compared to the turbine rotor balanced only at low speed with all mass bodies including blades.

Adaptive Vision-Based Method for Rotor Dynamic Balance System

This article presents a new adaptive vision-based method (AVBM) of performing automatic detection for rotor balancing, and the online implementation proved that the method achieved rapid real-time optimization of system balancing configuration for a rotor dynamic balance machine. The proposed AVBM integrated 3D sensors and dynamic balancing platform using 3D computer vision technique and dynamic balance algorithm to improve the efficiency of rotor dynamic balancing. AVBM applied 3D ToF sensors on active rotor dynamic balance machines to grab 3D point cloud of rotor shaft and balance sprues. By 3D depth data, the background noise can be removed to detect the positions of shaft center, key phasor and balance sprues of rotor automatically. After combining with unbalance vector from dynamic balancing machine, the AVBM system calculated the optimal balance configuration by the vector analysis algorithm. Compares to conventional methods, conventional rotor dynamic balancing process relies on technicians to mount washers on particular balance sprues based on their experience, therefore uncertainty causes productivity decline. Experiments in industrial examples showed that the proposed AVBM required fewer rounds to achieve acceptance, whereas the conventional industrial rotor balancing method performed by operators required more than three rounds in average. Consider the overall dynamic balancing process for the motor, the processing time required for each motor without AVBM was 348.9 seconds, and the daily rotor balancing count of each dynamic balancing machine was 83. The processing time with AVBM was shortened from 348.9 to 283.9 seconds, the daily rotor balancing count had increased from 83 to 101, and the production improvement had reached 22 %. That is, the proposed AVBM can accurately analyze the dynamic balance and greatly reduce the redundant dynamic balance operations. The main advantage of the proposed AVBM over conventional methods is its efficiency, effectiveness and robustness in online optimization of rotor dynamic balance.

Online measuring and estimating methods for the unbalancing vector of thin-disc workpiece based on the adaptive influence coefficient

The thin-disc part is the common part of the rotary mechanism. Because of the large rotating radius of the thin-disc part, the huge unbalancing vector may be formed even if the unbalancing mass is small. So, the unbalance of the thin-disc part is the important exciting factor of the rotary mechanism vibration. Based on the structural characteristics of the thin-disc part, the measuring and estimating methods for the unbalancing vector of the thin-disc workpiece are proposed based on the single-face influence coefficient method. The least square method is introduced to fit the fundamental frequency component from the vibration monitoring signal, and the fundamental frequency component is taken as the unbalancing vibration signal of spindle first. The influence coefficient between the trial weight face and vibration monitoring point on the spindle is tested by trial weight experiments second. The unbalancing vibration difference of the spindle, before and after the thin-disc workpiece is clamped, is monitored and used to estimate the unbalancing vector of the thin-disc workpiece based on the linear reversible principle of unbalancing excitation and vibration response. The signal separation accuracy of the least square method for unbalancing vibration has been proved by simulation and experiment methods. Considering that the accuracy of the influence coefficient may be influenced by the change of the spindle system kinetic characteristic parameters, the signal measurement, analysis error, etc., the adaptive method for the influence coefficient is proposed and proved by the experiment method in the article. The research results show that the unbalancing vector of the thin-disc workpiece can be measured and estimated before the workpiece is taken down from the machine tool spindle. The proposed method can be used to measure and estimate the unbalancing vector of the thin-disc workpiece without dynamic balancing machine, and the measuring efficiency and accuracy can be improved; the measuring cost can be reduced.

Dynamic Balance Method for Grading the Chain Drive Double Threshing Drum of a Combine Harvester

Although the individual threshing drum of a combine harvester was balanced on a dynamic balancing machine before it is assembled, there were still unbalances after multiple drums were assembled with the chain drive. In this paper, the double drums with a chain drive of a crawler combined harvester were selected as the research subject. The aim of this study was to develop a dynamic unbalance mode for grading chain drive double drums. Based on the dynamic unbalance characteristics of the main driven drum, the experimental research on the radial balance of the driven drum end face was carried out. It was known that the chain drive had a direct and obvious influence on the unbalanced phase of the drum. The unbalance of the drive load had an obvious effect on unbalanced amplitude of an active drum through the transfer characteristics of the chain drive. For the multi-stage transmission characteristics of a combine harvester, a step-by-step balanced grading chain drive double drum dynamic balancing method was practiced. Results showed that the unbalanced amplitude after balancing threshing drum I chain transmission mode of the combine harvester can be reduced by a maximum of 91%. Simultaneously, the unbalanced amplitude of threshing drum II can reduced by a maximum of 69.2%. The size and position of the wrap angle of the chain drive would directly affect the phase of the two equivalent unbalanced masses.

Calibration of a Hub Dynamic Balancing Machine Based on the Least Squares Method and Systematic Error Analysis

To resolve issues such as excessive residual vibrations and unsatisfactory balance effects in the balancing process, the particle swarm optimization (PSO)algorithm is combined with the least squares influence coefficient method of rotor dynamic balance to perform dynamic balance calibration based on the research of the least squares influence coefficient method of wheel dynamic balance. The influence coefficient generally has a large error due to the influence of the vibration measured value, thereby lowering the accuracy of the calibrated influence coefficient. Therefore, the maximum likelihood estimate (MLE) method is employed to address the influence coefficient error, and the result is compared with the calibration value of the influence coefficient (IC) method. The analysis results indicate that the residual value generated by the calibration of the influence coefficient through the maximum likelihood estimate (MLE) is 1.036 while the residual value obtained through the influence coefficient (IC) method is 1.513, suggesting that the former exhibits a smaller systematic error and is closer to the true value.

Development of a dynamic surface shape measurement for magnetic fluid

Traditional measurement techniques such as fringe and stereo projection can hardly measure the black surface shape of magnetic liquid in revolving container which has a cover to prevent the liquid spilling out. To solve this problem, a multi-step measurement method based on linear laser projection is proposed. Modulated laser by synchronous revolving chopper is introduced to obtain the steady projection light curve on the measured location of the magnetic fluid surface. In order to capture the instantaneous reflected light of the projection light curve, a camera used a long exposure time of shooting is used. Taking the advantages of multiple exposure luminance enhancement effect of long exposure time, pictures with high brightness and contrast projection light are obtained. The overall surface shape of the fluid can be reconstructed by many laser projection lines extracted from the pictures captured at different angles of revolving container. A high transparency acrylic cover is adopted to provide good sealing performance and light transmission quality in the experiment. On the base of correction of influence of refractive index of the acrylic cover, the height formula of magnetic fluid surface is derived. The camera installation angle and distance between the camera and the container are not required as the size of container are utilized to calibrate the camera. The relationship between image coordinates and world coordinates is also obtained. According to the height curves of the projection lines and their measuring angles on the container, 3-D surface shape of magnetic fluid is reconstructed. The surface shape is verified indirectly by using the imbalance of the container, and the relative unbalance errors between the measurement results and the results by Shenk dynamic balancing machine under different conditions are between 0.8% and 11%. Another performance experiment on measuring the surface shape of an rubber block indicates that the measurement range of the proposed method is that the slope of the measured surface must be less than 3.94, and the sensitivity is 0.18 mm. All performance of the proposed method is acceptable, so such a complex industrial problem is solved only by a daily digital camera.

Research on Dynamic Balance Adjustment Method of Single Braced Frame Gyroscope Rotor

The uneven mass distribution of gyro rotors results in vibration, rotation and drift of gyro rotors, which seriously affect the performance index and life of gyro rotors. However, because there is no rigid connection between the rotary shaft and the shell of the gyro rotor, the dynamic balancing machine can only balance the vibration component of the single braced frame gyroscope rotor, and can’t measure the gyro rotor’s rotation component. By analyzing the influence of uneven rotor mass distribution on the gyro rotor performance, a method of eliminating two rotational degrees of freedom of the gimbal in gyro rotor by mandrel is proposed, which makes the dynamic balancing machine directly measure the vibration component and the moving component of the gyroscope rotor, and simplifies the dynamic balancing debugging process.

Indirect Measurement of Rotor Dynamic Imbalance for Control Moment Gyroscopes via Gimbal Disturbance Observer.

The high-precision speed control of gimbal servo systems is the key to generating high-precision torque for control moment gyroscopes (CMGs) in spacecrafts. However, the control performance of gimbal servo systems may be degraded significantly by disturbances, especially a dynamic imbalance disturbance with the same frequency as the high-speed rotor. For assembled CMGs, it is very difficult to measure the rotor imbalance directly by using a dynamic balancing machine. In this paper, a gimbal disturbance observer is proposed to estimate the dynamic imbalance of the rotor assembled in the CMG. First, a third-order dynamical system is established to describe the disturbance dynamics of the gimbal servo system, in which the rotor dynamic imbalance torque along the gimbal axis and the other disturbances are modeled to be periodic and bounded, respectively. Then, the gimbal disturbance observer is designed for the third-order dynamical system by using the total disturbance as a virtual measurement. Since the virtual measurement is derived from the inverse dynamics of the gimbal servo system, the information of the rotor dynamic imbalance can be obtained indirectly only using the measurements of gimbal speed and three-phase currents. Semi-physical experimental results demonstrate the effectiveness of the observer by using a CMG simulator.

Low frequency high sensitive velocity pickup transducer for vertical dynamic balancing machine (VDBM)

ABSTRACTThe measurement of static and dynamic unbalance of satellite is carried out on vertical dynamic balancing machine (VDBM) [1]. The Velocity pickup is a transducer in VDBM, which measures the dynamic velocity due to static and dynamic unbalance and converts mechanical motion into voltage output, which controls measurement sensitivity of machine. In order to improve measurement sensitivity of balancing machine at low spin speed, a new velocity pickup with higher sensitivity is developed. A full scale development model of velocity pickup is developed and tested with VDBM. This paper gives the detailed description about design, analysis and sensitivity measurement of the low frequency high sensitive velocity pickup.

Study on the Frequency Compensation of the Dynamic Unbalance Signal Extraction for General Hard Bearing Dynamic Balancing Machine

When a dynamic balancing measuring system is equipped with velocity sensor as its vibration pick-up, the output signal of the sensor is proportional to the third power of rotating speed of the balancing operation. Generally a third order low-pass filter circuit is often used to eliminate the influence of rotating speed and suppress the high frequency interference as well. However, the frequency response of third order low-pass filter circuit can’t compensate completely for the response characteristic of the vibration system of balancing machine, which then causes measuring error. So, as a general purpose hard bearing dynamic balancing machine being suitable for a wide speed range, frequency compensation must be conducted. The approach of frequency compensation is classified into two broad types: hardware and software compensation. This paper conducts further research on these two methods to improve the accuracy of the measuring system and proves the accuracy and effectiveness of the two methods by signal simulation and field experiments.

Experimental study on pad temperature and film thickness of tilting-pad journal bearings with an elastic-pivot pad

For the failure damage of local melting caused by a high temperature rise of an in-service bearing, which is a three-pad tilting-pad journal bearing with an 800mm diameter and is used to support a 1150MW nuclear power generator, the structural parameters of the bearing were redesigned and an experimental study was performed to investigate the pad temperatures and film thicknesses of the redesigned bearing and the in-service bearing on a dynamic balancing machine. Test results indicate that the test scheme is feasible and effective, and the redesigned bearing has better performances than the in-service bearing.

Метрологические аспекты модели уравновешивания летательного аппарата на динамическом балансировочном стенде

Рассмотрены результаты разработки методики подтверждения характеристик точности низкочастотного вертикального динамического балансировочного стенда, предназначенного для контроля параметров массоинерционной асимметрии летательных аппаратов конической формы.

Dynamic Balancing of the Threshing Drum in Combine Harvesters – The Process, Sources of Imbalance and Negative Impact of Mechanical Vibrations

The purpose of this article is to present the description of the process of the dynamic balancing of threshing drum in combine harvesters as well as the sources of imbalance. The dynamic balancing analysis was carried out in production facility on dynamic balancing machine. Dynamic balancing of slats of the combine harvester threshing drum was determined by reference to the specified mass dynamic unbalance. The article also presents the influence of unbalanced machine elements on the human body.

Study on the Calibration of Dynamic Balancing Machine for Separating System Interference Vibration

The minimum achievable residual unbalance ratio emaris the index for evaluating the balancing capability of dynamic balancing machine. When the emaris expected to achieve to 0.1um grade or higher, to tap potential solely from the design of the signal conditioning circuits or the digital signal processing algorithm could not settle problems completely, equal importance should be paid on eliminating the influence of machine intrinsic interference vibration. Unfortunately, compared with much effort on the research and implementation of circuits and algorithm for unbalance signal extraction, little attention has been paid on the latter. This paper puts forward an interference vibration separation approach based on multi-point test-mass circulation calibration, to the purpose of improving the overall performance of balancing machine.The measurement system of a dynamic balancing machine composed of vibration mechanism, vibration pick-up sensor, signal conditioning circuits and the digital signal processing module, wherein the vibration mechanism locates on the front end and is of great importance. In the current design of dynamic balancing machine, there is a hypothesis that the vibration mechanism vibrates in the manner of simple harmonic oscillation forced by the unbalance of the under test rotate work piece and the amplitude and initial phase of that vibration are only related to the magnitude and angle position of the unbalance. In a practical balancing machine, however, the unbalance of driving devices, the coaxial error of the coupling or the vibration of the driving belt will incur additional vibrations to the vibration mechanism. Being of the same frequency or nearby frequency with the unbalance vibration, those interference vibrations are difficulty to remove by the signal conditioning circuits or the digital signal processing approach.Based on the invariability of the machine intrinsic interference vibration, this paper developed a circumference multi-point measurement and compound calibration method. The principle of the method will be introduced and analyzed in detail in the paper. Based on the vector operation and least square fitting to the unbalance vibration response with the obtained compound vibrations, the interference vibration can be separated to a satisfied extent. Experiments investigation is carried out on a hard bearing dynamic balancing machine, and the experiment results demonstrate the feasibility of the said method.

Dynamic Stiffness Measurement and Dynamic Behaviors Prediction of Bearing Support in Heavy Dynamic Balancing Machine

Dynamic Stiffness Measurement and Dynamic Behaviors Prediction of Bearing Support in Heavy Dynamic Balancing Machine

The Processing Technology and Dynamic Balancing of Turbocharger Rotor Parts

The passage analyzed the influence factors of dynamic balance of the turbocharger rotor. According to the structure of turbo rotor components and compressor impeller, the article proposes the matching process of impeller shaft and the selection of equipment model and expounds the importance of rotor dynamic balance. The working principles of two models of whole dynamic balancing machine are comparative analyzed, so as to provide a selection for processing choice.

Vibration Characteristic Analysis and Research of High Speed Dynamic Balancing Machine

Dynamic performance of high speed dynamic balancing machine directly affects the accuracy and safety of dynamic balancing machine. ANSYS 12.0 was used to establish the frame structure model in this paper. The four models of dynamic balancing machine were calculated respectively. The calculation results show that additional stiffness can greatly improve the natural frequencies of dynamic balancing machine. In addition, as the base is large, we can ignore the influence on natural frequencies caused by the base.