Modeling and Simulation for the Feed System of CNC Machine

2014 ◽  
Vol 496-500 ◽  
pp. 1024-1027
Author(s):  
Qin Wu ◽  
Jian Jun Yang ◽  
Chun Li Lei
Keyword(s):  
Driving Force ◽  
Simulation Analysis ◽  
Multiple Solution ◽  
Ball Screw ◽  
Nonlinear Stiffness ◽  
Cnc Machine ◽  
Feed System ◽  
Damping Force ◽  
System Use ◽  
Linear And Nonlinear

Study the linear and nonlinear stiffness dynamic characteristics of ball screw in feed system. According to the structure and the stiffness of ball screw, considering the influence of damping force, elastic force, friction force, driving force and load, establish the dynamic model of feed system. Use Linz Ted- Poincare (L-P) Method of singular perturbation to solve the model, obtain the quadratic approximate solution of the free vibration, analyze the multiple solution phenomenon of the model, and also conduct the numerical simulation analysis for the model.

scholarly journals Dynamic Modeling and Experiment Research on Twin Ball Screw Feed System Considering the Joint Stiffness

Symmetry ◽  
2018 ◽  
Vol 10 (12) ◽  
pp. 686 ◽  
Author(s):  
Meng Duan ◽  
Hong Lu ◽  
Xinbao Zhang ◽  
Yongquan Zhang ◽  
Zhangjie Li ◽  
...  
Keyword(s):  
Dynamic Modeling ◽  
Dynamic Characteristics ◽  
Friction Model ◽  
Numerical Control ◽  
Ball Screw ◽  
Cnc Machine Tools ◽  
Axial Stiffness ◽  
Cnc Machine ◽  
Feed System ◽  
Lumped Mass

It is of great significance to study the dynamic characteristics of twin ball screw (TBS) feed system to improve the precision of gantry-type dual-driven computer numerical control (CNC) machine tools. In this paper, an equivalent dynamic model of the TBS feed system is established utilizing lumped mass method considering the stiffness of joints. Equivalent axial stiffness of screw-nut joints and bearing joints are both calculated by Hertz contact theory. Furthermore, a friction model is proposed because the friction force of the screw nut affects the stiffness of the joints. Then, the friction parameters are obtained by using the nonlinear system identification method. Meanwhile, a finite element model (FEM) is developed to assess the dynamic characteristics of TBS feed system under the stiffness of joints. Finally, validation experiments are conducted, and the results show that the positions of the nut and the velocities of worktable greatly affect the dynamic characteristics of the TBS feed system. Compared with the theoretical calculation, FEM and experiments indicate that the dynamic modeling proposed in this article can reach a higher accuracy.

scholarly journals Analysis on Dynamic Contact Characteristics and Dynamic Stiffness Estimating Method of Single Nut Ball Screw Pair Based on the Whole Rolling Elements Model

2020 ◽  
Vol 10 (17) ◽  
pp. 5795
Author(s):  
Ye Chen ◽  
Chunyu Zhao ◽  
Zhenjun Li ◽  
Zechen Lu
Keyword(s):  
Machine Tool ◽  
Mass Production ◽  
Contact Stiffness ◽  
Dynamic Stiffness ◽  
Dynamic Contact ◽  
Ball Screw ◽  
Cnc Machine Tool ◽  
Cnc Machine ◽  
Feed System ◽  
Stiffness Model

The purpose of this paper is investigating the characteristics of dynamic contact and dynamic stiffness of the single nut ball screw pair (SNBSP). Then a new sensorless method is proposed to extract the SNBSP dynamic contact stiffness of a mass production CNC machine tool feed system. First of all, the transformation relationship between each coordinate system of SNBSP is established. Secondly, the dynamic model of all ball–raceway contact pairs is established. Based on this, a dynamic contact stiffness model is established. The dynamic contact parameters are obtained by the numerical method. It is found that the influence of screw speed on screw and nut raceway normal force distribution are opposite. This will affect the variations of dynamic contact stiffness. It is also clear that the effect of axial load on dynamic stiffness is significant. Then, an effective method is proposed to estimate the dynamic contact stiffness of a mass production CNC machine tool feed system without any external sensors. The axial force of feed system is estimated by using torque current of servo motor. Current signals can be obtained through FANUC Open CNC API Specifications (FOCAS) library functions, and then dynamic contact stiffness can be calculated through the stiffness model without external sensors. Finally, a feed system dynamic model is built, and the contact model and sensorless stiffness estimating method are verified by experiments in this dynamic system.

The Stiffness Analysis and Modeling Simulation of Ball Screw Feed System

2010 ◽  
Vol 97-101 ◽  
pp. 2914-2920 ◽  
Author(s):  
Qin Wu ◽  
Zhi Yuan Rui ◽  
Jian Jun Yang
Keyword(s):  
Machine Tool ◽  
Control Strategy ◽  
Feedforward Control ◽  
Dynamic Performance ◽  
Numerical Control ◽  
Ball Screw ◽  
Axial Stiffness ◽  
Cnc Machine Tool ◽  
Cnc Machine ◽  
Feed System

The computer numerical control (CNC) machine tool was investigated and the dynamics model for the servo feed system was established. Based on the fixing constraint of the ball screw, the mathematical models of axial stiffness and torsion stiffness are constructed. According to the effects of stiffness on the dynamic performance, the simulation model for CNC machine tool feed system with stiffness considered was set up by the dynamic simulation tool Simulink, and a curve representing the performance of the system was obtained. To reduce the effect of stiffness on the system, the feedforward control strategy is used for stiffness compensation. The simulation results show that the stability and response performances of the system are improved and the steady-state error of the system is reduced by the control strategy.

scholarly journals Hybrid Multi-Domain Analytical and Data-Driven Modeling for Feed Systems in Machine Tools

Symmetry ◽  
2019 ◽  
Vol 11 (9) ◽  
pp. 1156 ◽  
Author(s):  
Zaiwu Mei ◽  
Jianwan Ding ◽  
Liping Chen ◽  
Ting Pi ◽  
Zaidao Mei
Keyword(s):  
Analytical Model ◽  
Machine Tools ◽  
Data Driven ◽  
Ball Screw ◽  
Cnc Machine Tools ◽  
Cnc Machine ◽  
Feed System ◽  
Tracking Errors ◽  
Dynamic Tracking ◽  
Data Driven Modeling

Position error-compensation control in the servo system of computerized numerical control (CNC) machine tools relies on accurate prediction of dynamic tracking errors of the machine tool feed system. In this paper, in order to accurately predict dynamic tracking errors, a hybrid modeling method is proposed and a dynamic model of the ball screw feed system is developed. Firstly, according to the law of conservation of energy, a complete multi-domain system analytical model of a ball screw feed system was established based on energy flow. In order to overcome the uncertainties of the analytical model, then the data-driven model based on the back propagation (BP) neural network was established and trained using experimental data. Finally, the data-driven model was coupled with the multi-domain analytical model and the hybrid model was developed. The model was verified by experiment at different velocities and the results show that the prediction accuracy of the hybrid model reaches high levels. The hybrid modeling method combines the advantages of analytical modeling and data-driven modeling methods, and can significantly improve the feed system’s modeling accuracy. The research results of this paper are of great significance to improve the compensation control accuracy of CNC machine tools.

Evaluation of DC Servo Machine Tool Feed Drives as Force Sensors

1986 ◽  
Vol 108 (4) ◽  
pp. 279-288 ◽  
Author(s):  
J. L. Stein ◽  
D. Colvin ◽  
G. Clever ◽  
C.-H. Wang
Keyword(s):  
Machine Tool ◽  
Cutting Force ◽  
Force Sensor ◽  
Lumped Parameter Model ◽  
Ball Screw ◽  
Model Parameters ◽  
Cnc Machine ◽  
Feed System ◽  
Feed Force ◽  
System Components

Unmanned machine tools as part of an automated factory require reliable, inexpensive sensors to provide machine and process information to the controller. The electric current in the DC motor of a CNC machine tool can be inexpensively measured and used to calculate the tool/workpiece cutting force and the forces associated with drive system components. In order to characterize the bandwidth, sensitivity and accuracy of current monitoring on the feed system of a CNC lathe, a dynamic lumped parameter model of this sensor system is developed. The model is used to identify the system components that have a dominant effect on the behavior of the sensor. Tests were conducted in order to determine the model parameters, verify the model, and determine the signal-to-noise (S/N) ratio of the sensor. The bandwidth of this sensor is predicted to be 80 Hz. Tests show that the S/N ratio is low but can be improved by a trade-off with the system bandwidth. The bandwidth is limited by the characteristics of the SCR amplifier. In addition, the sensitivity and accuracy of calculating the feed force component of the cutting force from the total current used by the feed motor is limited by the pitch of the ball screw and friction coefficient variations in the slide. Feed system design changes, to improve the S/N ratio of the feed system as a tool and machine force sensor, are discussed.

Dynamic characteristics analysis and experimental of differential dual drive servo feed system

2021 ◽  
pp. 095440622110179
Author(s):  
Hanwen Yu ◽  
Laigang Zhang ◽  
Chong Wang ◽  
Xianying Feng
Keyword(s):  
Degrees Of Freedom ◽  
Electromechanical Coupling ◽  
Simulation Analysis ◽  
Drive System ◽  
Ball Screw ◽  
Parameter Method ◽  
Feed Speed ◽  
Feed System ◽  
Stick Slip ◽  
Low Speed

This paper presents the design for a new differential-dual-drive low-speed micro-feed mechanism. The ‘nut rotary ball screw pair’ is the main driving component of the mechanism. The screw and nut are each driven by a servo motor and these motors rotate in the same direction at a similar speed. The nonlinear factors such as friction and backlash can lead to unstable behaviours such as stick-slip and oscillation of the feed system. We use the Euler–Bernoulli beam elements, which have axial and torsional degrees of freedom, to describe the axial and torsional vibration of the ball screw, and use the spring-lumped parameter method to analyse other components of the feed system. An electromechanical coupling dynamic model with nonlinear factors of friction and clearance is established. Through simulation analysis and experiment, the difference in response of single-drive and differential-dual-drive systems under the influence of friction and clearance is studied. The results show that the nonlinear factors of friction and clearance have an influence on the feed speed of single-drive and differential-dual-drive system, but the low-speed micro-feed performance of the differential-dual-drive system is evidently better than that of the single-drive system. In the experiment, under the condition of screw single drive and differential dual drive, the critical crawling velocities of the table are measured. The experimental results are consistent with the simulation results, which verifies that the established models are reasonable. This lays a foundation for the design and research of the controller.

The Vibration Characteristic Analysis of Feed System of CNC Machine Tool

2013 ◽  
Vol 482 ◽  
pp. 169-173
Author(s):  
Qin Wu ◽  
Jian Jun Yang
Keyword(s):  
Machine Tool ◽  
Lagrange Equation ◽  
Contact Stiffness ◽  
Ball Screw ◽  
Cnc Machine Tool ◽  
Test Bed ◽  
Cnc Machine ◽  
Characteristic Analysis ◽  
Feed System ◽  
Vibration Displacement

The mathematical model of feed system of CNC machine tool was established base of Lagrange Equation and energy principle, then uses the Runge-Kutta method to solve the equation, and analyzes the influence that the parameters to the vibration displacement of ball screw. According to the result of orthogonal test, it is concluded that the most important three factors which influence ballscrew vibration displacement were the ball screw's lead h, the table quality m and the longitudinal contact stiffness kn in the connection of workbench and ballscrew. On the feed system test-bed, the longitudinal amplitude, torsional amplitude and horizontal amplitude of ball screw were measured, the results show the larger the ball screw's lead and the quality of workbench, the greater the amplitude of ball screw, the bigger the longitudinal contact stiffness kn, and the smaller the amplitude of screw.

scholarly journals Theoretical Calculation and Simulation Analysis of Axial Static Stiffness of Double-Nut Ball Screw with Heavy Load and High Precision

2019 ◽  
Vol 2019 ◽  
pp. 1-11
Author(s):  
Haitao Luo ◽  
Jia Fu ◽  
Lichuang Jiao ◽  
Fengqun Zhao
Keyword(s):  
Finite Element ◽  
Axial Load ◽  
Simulation Analysis ◽  
Hertzian Contact ◽  
Ball Screw ◽  
Deformation Model ◽  
Heavy Duty ◽  
Static Stiffness ◽  
Feed System ◽  
Friction Stir

Double-nut ball screws bear the action of bidirectional pretightening force, leading to the deformation of the contact area between the ball and the raceway. Under this condition, it is important to analyze and calculate the static stiffness of the ball screw. However, the conventional calculation method is inaccurate. Hence, a new method for the static stiffness analysis of a double-nut ball screw is proposed. Through the structural analysis of the ball screw and internal load distribution, a load deformation model was established based on the Hertzian contact theory. Through the load analysis of the ball screw, a static stiffness model of the ball screw was established and applied to a case study and a finite element simulation. The rigidity of THK double-nut ball screws used in the X-axis feed system of a high-stiffness heavy-duty friction stir welding robot (developed by the research group) was calculated. When the workload was lower than 1.1 × 104 N, the slope of the double-nut static stiffness curve increased significantly with the increase in the workload, and when the workload was greater than 1.1 × 104 N, its upward slope tended to stabilize. The simulated and experimental stiffness curves were in good agreement; when the external axial load was greater than 2.8 × 104 N, the stiffness value calculated using the finite element method gradually converged to the theoretical value; and when the axial load reached 3.0 × 104 N, the simulation and test curves matched well. The analysis method of the double-nut ball screw was found to be concise and accurate, and the stiffness curves calculated using the two methods were consistent. The simulation analysis of the static stiffness presented herein is expected to aid the design of double-nut ball screws of high-rigidity heavy-duty equipment.

Nonlinear Vibration Characteristics Analysis of CNC Machine Tool Feed System

2012 ◽  
Vol 472-475 ◽  
pp. 626-631
Author(s):  
Rui Cheng Feng ◽  
Zhi Yuan Rui ◽  
Qin Wu ◽  
Hai Yan Li
Keyword(s):  
Nonlinear Dynamics ◽  
Machine Tool ◽  
Dynamic Properties ◽  
Ball Screw ◽  
Elastic Displacement ◽  
Cnc Machine ◽  
Dynamics Model ◽  
Feed System ◽  
Linear Dynamics ◽  
Proposed Model

Considering the nonlinear characteristic of ball screw, a Duffing equation with damping is used to model the nonlinear dynamics of feed system by employing the elastic displacement method. Then by using the tools of phase trajectory map, Poincare section and bifurcation diagram respectively, structure of the proposed model is identified, meanwhile, the properties of bifurcation and chaos are judged. Numerical results show that as the feed system works, the screw nonlinear vibrates. Therefore, the dynamics response of the system cannot be described by a linear dynamics model. In other words, a nonlinear dynamics model must be employed to analyze the dynamic properties of the system. The proposed model has an advantage over the model characterized by a linear dynamics with multiple degrees since the latter is only applied to the system with high stiffness. In addition, the dynamics properties of the feed system are revealed as the stiffness is low or the support at both ends in varied. A test in a NC machine tool verified the validity of the analytic results.

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