Simulation approach for improving CNC milling machines accuracy for single axis motion (original) (raw)

Computer Simulation for the Study of CNC Feed Drives Dynamic Behavior and Accuracy

In the application of CNC feed drives it is desirable to predict the servo performance. By using computer simulation techniques it is possible to construct an accurate model of the servo drive. This simulation procedure makes it possible to anticipate machine design problems and correct them. This paper deals with a model of a feed drive, which consists of a motion control system driven by a DC motor. Both position and velocity feedback loops are present in the structure of the system. By means of MATLAB & Simulink software, simulation diagrams were built in order to test the behaviour of the system. Experimental data are also presented in order to confirm the accuracy of the theoretical model.

VIRTUAL MODELLING AND SIMULATION OF A CNC MACHINE FEED DRIVE SYSTEM

This paper deals with the virtual modelling and simulation of a complex CNC machine tool feed drive system. The first phase of the study was the modelling of a very complex structure of the feed drive which consists of many elements (position, velocity and current control regulators, actuators, mechanical transmission elements, etc.). All these elements have great influence on important parameters of the machine tool such as movement stability, positioning accuracy and dynamic stiffness. For the modelling of the system the Matlab-SIMULINK and Matlab-Sim Scape Toolbox software was used. The Matlab-Sim Scape Toolbox allowed us to use the complete CAD model of the geometry of the machine tool, automatically calculating the selected properties. The influence of changing and optimizing several feed drive parameters (position loop gain Kv, proportional gain Kp of the velocity controller, integral gain of velocity controller-Tn, electrical drive time constant Te, total moving mass m, sampling period Ts, etc.) on the positioning accuracy and the dynamic stiffness was simulated, tested and validated. The finished Matlab-Simulink and Sim Scape models were initially visualized in the Matlab program. They were very simplified, comparing with their later visualization in the Virtual Reality EON Studio program.

Motion control systems for machine tools - a mechatronic approach by means of simulation

Tuning the control parameters of the feed drives for existing state of the art CNC machine tools, or retrofitting obsolete machine tools requires a close understanding of the position control process. The use of a mathematical model of the feed drive, combined with a computer simulation process is needed in order to fulfill the above mentioned tasks. In this paper some simulation tools for studying the CNC motion control systems are presented. Both single axis positioning regime and biaxial linear and circular interpolation regime were taken into consideration. The main goal of the research was to offer a handson integrated simulation tools compatible and able to use for improving the performances of both the existing industrial CNC controllers and also the PC-based controllers for retrofitted machine tools.

Motion control of medium size CNC machine-tools - A hands-on approach

Proceedings of the 2012 7th IEEE Conference on Industrial Electronics and Applications, ICIEA 2012, 2012

This paperwork presents an integrated approach based upon simulation and experimental work for reducing the positioning errors of a small to medium size CNC machine-tools. The approach is intended to be used at the shop-floor level and therefore it is based upon a straight-forward model of the feed drive. The model was particularized with specific data from a CNC milling machine and simulation techniques were used to predict the behavior of the system. Only the control parameters of the feed drive which may be altered by the user, without modifying the structure of the CNC controller were taken into consideration and tuned. Simulation results and experimental data gathered before and after the tuning process were compared.

Real-time inclusive investigations for the selection of servo drive system of CNC machining centers

Journal of the Brazilian Society of Mechanical Sciences and Engineering, 2019

The capacity of modern computer numeric control (CNC) machine tool builds on the machine design (structural rigidity, drive system, control looping, etc.), machining process (cutting speed, feed rate and cutting forces) and environment (temperature and vibrations).The linear drive system of CNC machines consists of ball screw and its associated components. The servomotor drives the feed drive system in control conditions at required speed, and providing feedback to controller of the machine. Feed drive system is responsible for the performance of linear axis of machine. The performance indicators include positioning accuracy, repeatability and backlash. The required accuracy on workpiece relies on the torque/power of axis motors. The objective of this article is to derive an equation for the computation of torque for the feed drive system of CNC machines. We have proposed two simple and easiest method of computing torque. Firstly, we computed the torque required for the running of linear axis of machine under load conditions by the first method. Secondly, the verification of computed torque has been done by the second method. Thirdly, we have analyzed three major factors like rapid rate, weight over the system and lead of ball screw to study the behavior of torque. Finally, analytical estimations have been carried out for the validation of the deployed method.

The Influence of Servo Drive Control on the NC Vertical Milling Machine Dynamic Compliance

Journal of Manufacturing and Materials Processing, 2020

A model Numerical Control (NC) machine tool dynamic compliance is analyzed, including the influence of its mechanical structure and position control feed drive algorithms. The dynamic model of the machine tool is divided into two main parts, which are closest to the machining process. First, the milling head assembly group is presented as a system of one mass oscillating in a 2D plane and 3D space. Second, the motion axes assembly group, XY cross table with linear feed drive, is presented. A square 2×2 dimension matrix of the total dynamic compliance is evaluated within the feed drive control system included. Partial elements of the mechanical structure dynamic compliance matrix of the general N×N dimension are contained in the total dynamic compliance matrix.

Three axis deviation analysis of CNC milling machine

Journal of Mechatronics, Electrical Power, and Vehicular Technology, 2019

The manufacturing technology has developed rapidly, especially those intended to improve the precision. Consequently, increasing precision requires greater technical capabilities in the field of measurement. A prototype of a 3-axis CNC milling machine has been designed and developed in the Research Centre for Electrical Power and Mechatronics, Indonesian Institute of Sciences (RCEPM-LIPI). The CNC milling machine is driven by a 0.4 kW servo motor with a spindle rotation of 12,000 rpm. This study aims to measure the precision of the CNC milling machine by carrying out the measurement process. It is expected that the CNC milling machine will be able toperform in an optimum precision during the manufacturing process. Accuracy level testing is done by measuring the deviations on the three axes namely X-axis, Y-axis, and Z-axis, as well as the flatness using a dial indicator and parallel plates. The measurement results show the deviation on the X-axis by 0.033 mm, the Y-axis by 0.102 mm,...

CNC Motion Accuracy Analysis Under High Feedrate Values

2010

This study investigates the circular motion error in high feedrate through the Open CNC feedback signal. The motion accuracy is one of the most important factors to ensure the part quality in computerized numerical control (CNC) machine toools. There are several factors that degrade the control system performance, among then the mismatch of control loop gains, different axes dynamic response and servo lags. Regarding the CNC control system and its drives, there appears to be no specific standard tests that consider the influencing of high feedrate values on the control system performance and new tests must be developed. The objective of this study is to investigate the influence of high feedrate values on circular motion accuracy of the control system. In this study the position feedback signal of an open CNC installed on a High Speed Machining Center were measured and analyzed. The results shows that the control system studied provided good behavior for the circular deviation in hi...

Design and Development of a CNC Mill Trainer by using Modern DDCSV1 CNC Motion Controller

International Journal for Research in Applied Science & Engineering Technology, 2020

CNC machine tools are currently predominating in the machine-building industry. Generally, these machine tools are equipped with control systems supplied by the world's leading manufacturers, such as Siemens and Fanuc are very expensive. In parallel, many cheap amateur and semi-professional CNC machine tool solutions are being developed. One of the biggest challenges today is how to make the CNC technology affordable, simpler and available to an extent that even occasional user can think of owing such technology. The main standard components required for developing the prototype of machine tool structure has been selected following the approach of kind of loading the machine tool will be subjected. A systematic study has been done for the selection of the drive motors, controllers and spindle drive. The objective of maximizing the tool traverse in X,Y and Z direction so to enable to cutting tool to approach the maximum machining volume for material removal subject to the constraint of sizes of standard available machine components used in CNC machine. I. INTRODUCTION With the ongoing development of technology and economy, new industrial requirements such as high precision, good quality, high production rates and low production cost are increasingly demanded. Most of such requirement, including dimensional accuracy, conformance to tolerances of finished products and production rates can be met with better machine tools. The traditional design philosophy of machine tools is multifunctional and highest precision possible. For example, a shank with spindle together with tailstock can be added onto a standard three axis vertical milling machine to become a multifunction drilling-milling-turning machine, meaning the machine tool is design to be used for multiple purposes instead of single purpose. However with the dramatic increase of industry varieties and the growing demand of miniature products, these general purpose machine tools are not efficient, either in term of machine time or cost, in manufacturing products with special sizes and precision requirements.

Analytical modeling of the CNC machine axis motion in high-speed milling with local smoothing

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