Thermal Error Compensation for a High Precision Lathe to Improve Machining Accuracy

2009 ◽  
Author(s):  
Byung-Sub Kim ◽  
Young-Chan Song ◽  
Chun-Hong Park ◽  
Jong-Kweon Park
Keyword(s):  
High Precision ◽  
Temperature Control ◽  
Error Compensation ◽  
Thermal Error ◽  
Experimental Results ◽  
Machining Accuracy ◽  
Thermal Drift ◽  
Temperature Changes ◽  
Precision Machines ◽  
Thermal Error Compensation

High precision machines require very stable operational environment: temperature control and vibration isolation. Tight temperature control for machines usually demand high cost to operate air conditioners. Some of high precision machines require the ambient temperature changes to maintain within ±0.1 degrees. In this paper, we present a thermal error compensation scheme and experimental results for improving machining accuracy of a high precision lathe. The testbed lathe has X- and Z-axes and they are driven by linear motors and hydrostatic oil bearing. Due to the temperature changes of the ambient air and supplied oil to the hydrostatic bearing, thermal deformation is generated and measured to be as much as 200–300 nanometers. To identify the dynamic relations between the temperature changes and the thermal drift, a state-space model is used in which state variables are constructed from the input measured temperatures and the output thermal drift data. The identified model is implemented in a servo control loop and the predicted thermal error is compensated by subtracting the predicted thermal drift from the servo command. In our simulation, a thermal error of 97 nanometers RMS over 3 hours is reduced to 55 nanometers RMS. Experimental results show an average of 24% reduction in thermal drift and support the validity of our approach.

Thermal Error Analysis and Compensation Technology for High Precision Aspheric Measuring Platform

2013 ◽  
Vol 712-715 ◽  
pp. 1571-1575
Author(s):  
Feng Yang ◽  
Qia Heng Tang ◽  
Yin Biao Guo
Keyword(s):  
Error Analysis ◽  
High Precision ◽  
Heat Balance ◽  
Error Compensation ◽  
Thermal Deformation ◽  
Thermal Error ◽  
Positioning Error ◽  
Compensation Model ◽  
Balance State ◽  
Thermal Error Compensation

In this paper, a thermal error analysis and compensation method for a high precision aspheric measuring platform driven by a linear motor system is presented. After analyzing the heat source of thermal deformation, the thermal deformation of guide is selected to be object, and the thermal analysis method of guide in heat balance state is proposed. According to the motor temperature at different positions, the thermal error curve of guide is obtained through simulation. Modeling the global positioning error of measuring platform and the compensation model of thermal error using polynomial fitting, the thermal error compensation experiments is implemented by applying compensation system of measuring platform's controller. The experimental results show that the maximum positioning error in heat balance state is reduced from 1.5μm to 0.7μm, which verify the validity of thermal error compensation model.

Clustering Regression Modeling for Gear Hobbing Machine Thermal Error Compensation

2009 ◽  
Vol 416 ◽  
pp. 401-405
Author(s):  
Qian Jian Guo ◽  
Xiao Ni Qi
Keyword(s):  
Error Compensation ◽  
Thermal Error ◽  
Regression Modeling ◽  
Error Model ◽  
Error Modeling ◽  
Machining Accuracy ◽  
Thermal Error Modeling ◽  
Gear Hobbing ◽  
Thermal Error Model ◽  
Thermal Error Compensation

This paper proposes a new thermal error modeling methodology called Clustering Regression Thermal Error Modeling which not only improves the accuracy and robustness but also saves the time and cost of gear hobbing machine thermal error model. The major heat sources causing poor machining accuracy of gear hobbing machine are investigated. Clustering analysis method is applied to reduce the number of temperature sensors. Least squares regression modeling approach is used to build thermal error model for thermal error on-line prediction of gear hobbing machine. Model performance evaluation through thermal error compensation experiments shows that the new methodology has the advantage of higher accuracy and robustness.

Selecting of the Temperature Measurement Points for Positioning Platform with Large Trip and High Precision Thermally Induced Error Compensation Model

2013 ◽  
Vol 431 ◽  
pp. 132-136
Author(s):  
Ji Zhu Liu ◽  
Wei Wei Yang ◽  
Yang Jun Wang ◽  
Tao Chen ◽  
Ming Qiang Pan ◽  
...  
Keyword(s):  
Temperature Measurement ◽  
High Precision ◽  
Error Compensation ◽  
Thermal Error ◽  
Thermal Conditions ◽  
Grey System Theory ◽  
Grey System ◽  
Thermal Displacement ◽  
Thermally Induced ◽  
Thermal Error Compensation

In the technology of thermal error compensation in positioning platform with large trip and high precision, selecting the temperature measurement points rationally is particular important for successfully establishing the model of compensation. The method uses simulation to track platform heat distribution and thermal deformation under various thermal conditions. Temperature variables are grouped by different surfaces of the platform. Then a degree of grey incidence from grey system theory is introduced to identify the key temperature measurement points of each surface. Through the experiment data of thermal stress coupling analysis on the platform, the degree of correlation between all temperature measurement points and thermal displacement can be solved. The key temperature measurement points are confirmed by the largest value of the degree of correlation of each surface.

Thermal Characteristic Analysis on a High Precision Turning Center’s Headstock

2013 ◽  
Vol 655-657 ◽  
pp. 305-309
Author(s):  
Yao Man Zhang ◽  
Ren Jun Gu ◽  
Jia Liang Han
Keyword(s):  
High Precision ◽  
Error Compensation ◽  
Thermal Characteristic ◽  
Thermal Characteristics ◽  
Thermal Error ◽  
Linear Regression Method ◽  
Characteristic Analysis ◽  
Precision Turning ◽  
Turning Center ◽  
Thermal Error Compensation

The performances of the high precision turning center will be influenced by the thermal characteristics of the headstock seriously, and accurately predict thermal characteristics of the headstock are helpful to improve the design level. The headstock of a high precision turning center produced by some plant has been regarded as the research objects of the paper. First the steady temperature distribution and thermal deformation of the headstock were calculated based the finite element analysis models of the headstock. Then the temperature sensitive points of the headstock were obtained by using the grey incidence analysis method. Finally the thermal error compensation model was built by using multiple linear regression method. The study lays a foundation for the thermal error compensation of the headstock of the turning center.

Research on Volumetric Error Measurement, Modeling and Compensation for NC Machine Tools

2014 ◽  
Vol 513-517 ◽  
pp. 4202-4205
Author(s):  
Hong Xin Zhang ◽  
Qian Jian Guo
Keyword(s):  
Machine Tool ◽  
Error Compensation ◽  
Machine Tools ◽  
Thermal Error ◽  
Error Modeling ◽  
Cnc Machine Tools ◽  
Machining Accuracy ◽  
Volumetric Error ◽  
The Impact ◽  
Thermal Error Compensation

With the increasing requirements of the machining accuracy of CNC machine tools, the impact of thermal deformation is growing. Thermal error compensation technology can predict and compensate the thermal errors in real-time, and improve the machining accuracy of the machine tool. In this paper, the research objects of thermal error compensation is expanded to the volumetric error of the machine tool, the volumetric error modeling of a three-axis machine tool is fulfilled and a compensator is developed for the compensation experiment, which provides scientific basis for the improvement of the machining accuracy.

Thermal error compensation based on genetic algorithm and artificial neural network of the shaft in the high-speed spindle system

2016 ◽  
Vol 231 (5) ◽  
pp. 753-767 ◽  
Author(s):  
Chi Ma ◽  
Liang Zhao ◽  
Xuesong Mei ◽  
Hu Shi ◽  
Jun Yang
Keyword(s):  
Neural Network ◽  
Genetic Algorithm ◽  
Neural Networks ◽  
Error Compensation ◽  
High Speed ◽  
Back Propagation ◽  
Thermal Error ◽  
Machining Accuracy ◽  
Spindle System ◽  
Thermal Error Compensation

To improve the accuracy, generality and convergence of thermal error compensation model based on traditional neural networks, a genetic algorithm was proposed to optimize the number of the nodes in the hidden layer, the weights and the thresholds of the traditional neural network by considering the shortcomings of the traditional neural networks which converged slowly and was easy to fall into local minima. Subsequently, the grey cluster grouping and statistical correlation analysis were proposed to group temperature variables and select thermal sensitive points. Then, the thermal error models of the high-speed spindle system were proposed based on the back propagation and genetic algorithm–back propagation neural networks with practical thermal error sample data. Moreover, thermal error compensation equations of three directions and compensation strategy were presented, considering thermal elongation and radial tilt angles. Finally, the real-time thermal error compensation was implemented on the jig borer’s high-speed spindle system. The results showed that genetic algorithm–back propagation models showed its effectiveness in quickly solving the global minimum searching problem with perfect convergence and robustness under different working conditions. In addition, the spindle thermal error compensation method based on the genetic algorithm–back propagation neural network can improve the jig borer’s machining accuracy effectively. The results of thermal error compensation showed that the axial accuracy was improved by 85% after error compensation, and the axial maximum error decreased from 39 to 3.6 µm. Moreover, the X/ Y-direction accuracy can reach up to 82% and 85%, respectively, which demonstrated the effectiveness of the proposed methodology of measuring, modeling and compensating.

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