High-speed Electric Spindle Research Articles

Research on High-speed Electric Spindle Cooling Devices and Thermal Error Compensation Technology

Background: When computerized numerical control (CNC) machine tools are working, the electric spindle generates serious heat, which can easily cause the thermal elongation of the spindle and generate thermal errors. Designing cooling devices to control the generation of thermal errors in the spindle and utilizing thermal error compensation techniques for error compensation are essential for improving machining quality and productivity. Objective: By summarizing the current status of research on cooling devices and compensation technology of electric spindles in recent years, some conclusions have been drawn in this work to propose the future research direction. Methods: By reviewing patents on cooling devices and thermal error compensation technology of high-speed electric spindles published in recent years, we have explored the ideas for the improvement of existing cooling devices and compensation technology. Results: Some problems of the patents on current cooling devices and thermal error compensation technology are analyzed, and future research directions are proposed, respectively. Conclusion: As spindle power and speed continue to increase, the existing spindle cooling device and compensation technology also need to be continuously improved. Designers use intelligent technology to monitor the temperature changes during the work of the spindle and fast and accurate control of the cooling system so that the high-speed spindle cooling device tends to be intelligent. Aiming at the thermal error generated in the spindle working process, the designer enhances the error compensation effect by continuously improving and upgrading the key steps in the thermal error compensation technology, which in turn improves the spindle machining accuracy.

Modeling and compensation of the axial thermal error of electric spindles based on HHO-GRU method

As the core component of precision CNC machine tools, a lot of heat is generated from the internal heat source of electric spindles during operation, resulting in thermal deformation and thermal errors that affect machining accuracy. Thermal error compensation is an economical method for reducing thermal errors, through which the impact of thermal errors on machining accuracy can effectively decrease. Taking a high-speed electric spindle as the research object, the temperature measurement points are selected as its front and rear bearing seat, as well as some positions far from the heat source. The temperature changes at the front and rear bearing as well as in the environment are monitored, then the thermal errors are measured using a Lion spindle rotation accuracy instrument. The optimal training parameters of the gated recurrent unit (GRU) network are optimized utilizing the global optimization ability of a Harris Hawks optimizer (HHO). Finally, the thermal error prediction model of the GRU electric spindle optimized using the Harris Hawks optimizer (HHO-GRU) is established, based on which axial thermal error compensation experiments are conducted. The results show that using the HHO-GRU prediction model for compensation, the axial thermal errors of the electric spindle can be reduced by more than 80%, which can be controlled within 5 μm.

Optimization of cooling water jacket structure of high-speed electric spindle based on response surface method

In high-precision machining machine tools, the high-speed electric spindle is the fundamental transmission component. Nonetheless, the electric spindle's small and tightly sealed internal structure may result in insufficient heat dissipation, resulting in significant heat accumulation during continuous operation. This might induce thermal displacement of the spindle and reduce machine tool machining precision. A response surface was established by a 2-factor 3-level interaction experiment utilizing Design-expert software to reduce the heat displacement of the electric spindle. The electric spindle cooling water jacket was optimized and front and rear bearing cooling water channels were added based on the response surface results. The thermal-solid coupling simulation was carried out using ANSYS, and the optimized data for the front and rear bearing temperature, as well as spindle thermal displacement, were obtained through simulation analysis. Comparing the simulation with the experimental data, it was found that the front and rear bearing temperature decreased by 4.34 °C and 8.97 °C, respectively, and the spindle thermal displacement was reduced by 16.57 μm, resulting in improved machining accuracy. The service life of the bearings was further prolonged by the decreased thermal stress between the inner and outer rings and the balls of the front and rear bearings.

Simulation analysis model of high-speed motorized spindle structure based on thermal load optimization

High-end CNC machine tools' primary transmission mechanism is a high-speed electric spindle. Thermal displacement of the spindle occurs as a result of heat created inside the spindle during transmission, which has an impact on the machining precision of high-end CNC machine tools. Establishing a high-precision motorized spindle simulation model is crucial because it serves as a foundation for optimizing and testing the motorized spindle's construction and material, adjusting for thermal errors, and estimating its life. The thermal-solid coupling model of the motorized spindle is created by Ansys based on the experimental data of temperature and thermal displacement of the A02 motorized spindle and in accordance with the boundary conditions. The accuracy of front and rear bearings is 93.42% and 90.52%, respectively, when compared to experimental data, and the accuracy of axial thermal displacement is 95.16%. Finally, the motorized spindle is optimized to extend its service life after the thermal displacement, stress, and strain of the bearing are model.

Thermal error modeling of electrical spindle based on optimized ELM with marine predator algorithm

High-speed electric spindle is an important part of computer numerical control (CNC) machining equipment, and the thermal displacement generated by the electric spindle during operation affects the electric spindle machining stability and machining accuracy. Error compensation for the high-speed motorized spindle can well compensate for the influence of thermal displacement on machine tool processing. Therefore, the prediction of thermal displacement of electric spindle is particularly important. In this paper, firstly, the temperature field information is obtained by simulating and analyzing the calculation of the heat generation and heat exchange inside the electric spindle. Set up the experimental platform with reasonable temperature measurement points according to the simulation results; secondly, the temperature sensitive points are screened by fuzzy C-mean clustering algorithm and Pearson correlation coefficient, which can effectively improve the covariance and correlation between temperature variables; finally, based on the screened data for thermal error modeling, an optimized extreme learning machine based on marine predator algorithm (MPA-ELM) is provided to predict the thermal displacement of electric spindles model. And comparing the model accuracy of extreme learning machine (ELM), MPA-ELM and extreme learning machine optimized by genetic algorithm (GA-ELM), the experimental data show that MPA-ELM has better prediction accuracy.

Thermal error modeling of high-speed electric spindle based on Aquila Optimizer optimized least squares support vector machine

The thermal error of electric spindle is an important factor affecting the machining accuracy of machine tools. To establish the thermal error prediction model, the thermal characteristics of A02 electric spindle were simulated and analyzed by ANSYS, to determine the best temperature measuring point. The temperature and thermal error of A02 electric spindle at different rotational speeds were obtained by thermal characteristics experiment. Through the combination of systematic clustering and grey relational analysis, four best temperature measuring points were selected from ten temperature measuring points. A prediction model of least squares support vector machine (LSSVM) optimized by Aquila Optimizer (AO) is established and compared with the model optimized by Particle Swarm Optimization (PSO), it is superior to the latter in prediction accuracy (η), goodness of fit (R2), root mean square error (RMSE) and mean absolute error (MAE). The AO-LSSVM prediction model based on experimental data has a prediction accuracy of more than 94% for the thermal error of motorized spindle and has good stability and generalization ability.

Thermal error modeling of electric spindle based on particle swarm optimization-SVM neural network

High-speed electric spindle is an important part of computer numerical control (CNC) machining equipment. The thermal displacement generated by the electric spindle during operation is the main reason that affects the machining stability and machining accuracy of the electric spindle. Compensating the thermal error of the high-speed electric spindle can effectively improve the CNC machining. Improve equipment processing performance. Therefore, it is particularly important to establish the accuracy of the thermal error prediction model. Taking the A02 high-speed electric spindle as the research object, ANSYS is used to analyze the thermal characteristics of the electric spindle, and the temperature and thermal displacement monitoring points of the electric spindle are arranged according to the simulation results, and the temperature and thermal displacement data of the monitoring points under different rotational speeds are collected; using K-means to classify temperature measurement points, uses the gray relation analysis degree to determine the correlation between the temperature measurement point and the thermal displacement data, and selects 4 temperature-sensitive points from 10 temperature measurement points. Finally, particle swarm optimization (PSO) is used to optimize the penalty factor and kernel function of support vector machine (SVM), and the PSO-SVM prediction model is established to compare with the neural network prediction model of SVM and genetic algorithm (GA) optimized SVM. The results show that PSO-SVM has better robustness, stability, and generalization ability.

МЕТОДИКА ВЫБОРА ПАРАМЕТРОВ ФУНКЦИОНИРОВАНИЯ ЭЛЕКТРОШПИНДЕЛЯ С АЭРОСТАТИЧЕСКИМИ ОПОРАМИ ПРИ РАЗДЕЛЕНИИ ПОЛУПРОВОДНИКОВЫХ ПЛАСТИН НА КРИСТАЛЛЫ. ЧАСТИ 2–3

The article presents the results of studies of the shaft oscillation processes of a precision horizontal highspeed electric spindle with aerostatic radial and axial supports, used at Planar OJSC in equipment for separation of semiconductor plates into crystals. The studies were carried out using the developed mathematical models that take into account the design features of these electric spindles, including the cantilever mounting of the cutting tool, the imbalance of the diamond disc with the mandrel and the mass ratio of the main components of the electric spindle, as well as the results of their full-scale tests. Based on the analysis of the data obtained, regularities are shown that connect the amplitude values of the oscillations of the electric spindle shaft with the imbalance of the diamond disc with the mandrel and the rotational speed of the electric spindle, which made it possible to propose engineering dependences for choosing the permissible values of the imbalance and rational, from the standpoint of resonance conditions and permissible shaft oscillations, rotational speed of the electric spindle. Recommendations have been developed for the creation of a system for monitoring and active control of the parameters and functioning of the electric spindle in the process of separating semiconductor plates into crystals, which make it possible to use the resonant mode of radial oscillations to improve cutting conditions, excluding direct contact of the working surfaces of aerostatic supports, their seizure and loss of performance of the electric spindle. The article presents a method of selecting the operation parameters of a high-speed precision horizontal electric spindle with aerostatic radial and axial supports and a cantilever mounting of a diamond cutting disc. It is based on the analysis of the simulation results of shaft forced oscillations and data on the shaft oscillations during the operation of the electric spindle with different rotation frequencies and imbalances. The results obtained can be used to monitor shaft oscillations during the operation of the electric spindle, while the high operation efficiency of which is achieved by adaptive control of rotation frequencies taking into account the amplitudes of these oscillations.

The Influence of Centrifugal Force on the Interference Fit of High-Speed Electric Spindle

The letter presents an analysis of interference fit of the electric spindle at different rotor speeds due to the influence of centrifugal force and provides a theoretical formula showing the relationship of the speed, stress on the rotation speed. The letter also established a finite element model of the interference fit. The study found that as the rotation speed increases, the interference and contact stress between the spindle and the rotor gradually decrease, and the reduced speed is proportional to the square of the rotation speed.

Calculation and analysis of critical speed of high speed motor spindle rotor system

The traditional transfer matrix method used to calculate the critical speed of high-speed spindle motor rotor system will produce large errors. Taking the 170SD30 electrospindle as the analysis object, a high-speed electric spindle dynamics theoretical model was established based on the Riccati method, using Matlab to program and calculate the kinetic parameters of the first three critical speeds and natural frequencies of the high-speed spindle. Finally, the simulation data was compared with experimental data. The results show that the Riccati transfer matrix method is 2.3% more accurate than the traditional transfer matrix method, and it verifies the accuracy and feasibility of the Riccati transfer matrix method, and is of great significance to effectively guide the analysis and design of high-performance and high-speed motor spindle.

Based on ANSYS Workbench High Speed Electricity Spindle Dynamics Characteristic Analysis

This paper describes the inherent characteristics, dynamic response and dynamic stability dynamics of vibration capability that impacts of high-speed electric spindle. Taking the high-speed, high-power electric spindle milling center on as the object of the research, modal analyzing of electric spindle with the finite element software ANSYS Workbench, researching the spindle modes, natural frequencies and critical speed of electric spindle, to get each frequency and vibration type, pointed the affection of what spindle away from the anti-vibration frequency requirements, well before bearing stiffness and damping of the vibration to the spindle system. It provides the necessary basis for further dynamic analysis by modal analysis.

Fault Detection of a High-Speed Electric Spindle

The high-speed electric spindle is the key part of the machining center which performing high speed precision machining. In order to ensure the electric spindle running under the smooth and steady state, it is necessary to prevent and discover the abnormities during the running process of the electric spindle by the experimental test and analysis. In this paper, the vibration order analysis method combined with the experimental modal test is utilized to measure and diagnose the abnormities of a high speed electric spindle.

The Inner Hole Precision Detection of Precision Machining Zirconia Ceramics Spindle

The high-precision component named full ceramic high-speed electric spindle is used in high speed NC machine tools. Electric spindle have very high demand for the stability and dynamic balance of ceramic spindle when high-speed rotation. In order to ensure the smooth operation of high-speed spindle and realize the dynamic balance of the spindle, it is necessary to make a rigorous precision testing for the precision-processed spindle and obtain reliable data to meet the design standards and performance requirements of all ceramic high-speed spindle. In this paper, contact Surtronic25 type roughness measuring instrument is used for surface roughness analysis, and Leitz ultra PMM-C12.10.7 type tri-ordinate measuring machine is used for the roundness and cylindricity testing analysis of spindle hole, which can make the surface roughness, roundness, and cylindricity of the precision-processed zirconia ceramic spindle pore ​​to meet the design requirements and provide reliability safeguard to promote the using life and high-speed dynamic balance stability of the whole electric spindle.

Study of the Method on Cutting-Force Modeling Based on the Current of High-Speed Electric Spindles

It is important to build the models for calculating the cutting-forces in high-speed machining, but it is difficult as the special test-bed with the cutting-force measurement system is complicated, cost much and cannot be applied directly on general machining tools. Aiming at the problems above, a new method was put forward about cutting-force modeling based on the current of high-speed electric spindles, in which the cutting-force models could be gained indirectly by analyzing the built-in motor current and the data gotten from cutting experiments on those general machining tools which are installed with electric spindles. Then on a vertical milling machine tool which is equipped with a high-speed electric spindle, a model for calculating the milling force was gotten using the method put forward by this paper. The results show that the method is simple and easy to be used in routine machine tools in plant spots and need no any special test-beds and any complicated measurement systems possessed only in the laboratory conditions.