FACTORS AFFECTING THE ACCURACY OF POSITIONING OF (original) (raw)
Related papers
Positioning Accuracy of Non-Conventional Production Machines
The paper deals with machines employing parallel-kinematics structures (PKS). They represent a relatively new generation of machine tools. Depending on the number of struts, the machines are referred to as hexapod or tripod machines. Such machines offer several advantages comparing to the conventional machine tools with serial kinematics, such as high flexibility, high stiffness, and high accuracy. It is very suitable for High- Speed-Machining (HSM), light machining and has received a wide interesting in manufacture industry. To achieve a desired positioning accuracy and stability, the static and dynamic properties of the machine must be searched and mathematically described. The calculation of the estimate of positioning deviation, including respective uncertainty and covariances, is much more complicated task comparing to the serial kinematics.
Statistical analysis of positioning error of a CNC milling machine
Journal of Manufacturing Systems, 1982
The characteristics of the positioning error of a NC milling machine were studied through statistical analysis. It was found that (1) the mean of the error is significantly affected by the table position, (2) the variances of the error at different table positions are from the same population, and (3) the effect of the feedrate on positioning error is not significant. Also, a software correction technique was applied and workpiece error was decreased by 40%.
Precise Positioning Control Strategy of Machine Tools: A Review
Journal of Telecommunication, Electronic and Computer Engineering, 2017
In this article, a precise positioning control strategy for the nonlinearity of machine tools is thoroughly reviewed. Precise positioning is crucial in machine tools industry where nonlinear phenomenon must be considered. Therefore, this paper aims to review various techniques used to enhance the precision of nonlinearity of machine tools. In the introduction, a significant review of machine tools is discussed based on deadzone phenomenon and high bandwidth. After that, linear control strategies are reviewed involving Proportional-Integral-Derivative (PID) and Cascade P/PI controller. This is followed by nonlinear control strategies, Nonlinear PID (NPID), Adaptive NPID (ANPID), Feedforward NPID (FNPID), Adaptive Robust Controller (ARC), Nominal Characteristics Trajectory Following (NCTF) controller and lastly, the fuzzy and neural network control is then reviewed. Finally, conclusions are presented according to the past researches conducted. Further studies regarding the topic can b...
Accuracy Enhancement of CNC Turning by Linear Positioning Error Compensation
2019
1MSc Researcher, Mechanical Department, Faculty of Engineering-Helwan, Helwan University, Cairo, Egypt 2Professor, Mechanical Department, Faculty of Engineering-Helwan, Helwan University, Cairo, Egypt 3Associate Professor, Mechanical Department, Faculty of Engineering-Helwan, Helwan University, Cairo, Egypt 4Associate Professor, Electrical Power and Machines Department, Faculty of Engineering-Helwan, Helwan University, Cairo, Egypt ----------------------------------------------------------------------***--------------------------------------------------------------------Abstract This paper proposes a systematic checking and compensation for positioning errors of turning CNC machine tools which is low cost and demands little time. The study aims to identify axes errors without the need to in-process sensing or laser measurements such as ball-bar or laser interferometer systems, the estimation of positional errors is based on an assessment of the target turning CNC Machine tool by che...
2014
The three-axis machine tools produce an inaccuracy at the tool tip which is caused by kinematics parameter deviation resulting mainly from manufacturing error and assembly error. Here, all linear axes are theoretically perpendicular (dot product, cos 90 o = 0) to each other and directed along the X, Y, Z coordinate, but in working machines, the axes are nearly perpendicular (cos 89.9 o 0) because of the reasons mentioned above. This kind of error can be taken into consideration only by the precise description of the actual kinematics of the machine tool. This paper attempts to develop a generalized error model for the effects of positioning errors of the components of the kinematic chain of a machine in the work space and the results obtained by this model have been verified experimentally. The mathematical model of the volumetric error, based on positioning error component, has been derived and the effect of error component on the volumetric accuracy at the cutting point has been...
Kinematics of Positioning Device for Material Handling in Manufacturing
Acta logistica
Different types of robots are used in many areas of industry. Industrial manipulators are used to ensure productivity and flexibility in automated production lines. Most of them is used for tasks that automatically repeat the same operation in a familiar environment. The key element in the development and analysis of industrial robots is their kinematic analysis. The article deals with the kinematic analysis of this positioning equipment. Individual relations of kinematic quantities are plotted graphically. Matrix methods were used for the analysis.
Motion accuracy of NC machine tools
… of the 9th WSEAS International Conference …, 2008
Abstract: Modern CNC machines have two principal systems: the cutting system and feeding system. Work piece accuracy is the overall outcome of cutting and feeding systems. This paper investigate the contour errors (circular and square corner path) on the bases of a ...
Proceedings of International Conference on Leading Edge Manufacturing in 21st century : LEM21
Ihis paper describes the dynamic synchronous accuracy of translational and rotational axes in 5-axis machining centers. ln this study, non-uniform 3-axis synchronous motion was investigated in order to estimate the dynamic synchronous accuracy. A dynarnic model ofthe each axis including a rotary axis was developed, and the synchronous motion was simulated, The dynamic model mainly consists of a moment of inenia friction forces, a velocity controller and a position one. As the results ofexperirnent and simulation, it is clarified the developed model can express the experimental results accurately. In addition, a rnethod that can improve the synchronous accuracy is proposed, and its effectiveness is verified by the deve]oped dynamic model.