Machine tool 3D volumetric positioning error measurement under various thermal conditions

This paper presents the design of a precise “ball-column” device to efficiently and accurately measure the geometric error terms of both rotary axes of the five-axis machine tool. A geometric error measurement method of spherical contact was proposed based on the influence of the geometric error term from a five-axis machine tool rotating axis on the integrated geometric error of the machine tool. A multiple degree of freedom, step-by-step contact method based on on-machine measure for measuring the spherical center point is proposed, and the solution formula of each geometric error term of the rotating axis is established, respectively. This method can identify 12 geometric errors based on the influence of one rotating axis on another rotating axis after long term operation. The spatial error field of the five-axis machine tool was constructed by analyzing the error law of the two rotating axes of machine tools based on various positions and postures. Finally, after the comparison of the experiment, the results showed that the accuracy of the developed error measurement device reached 91.8% and the detection time was as short as 30–40 min.

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Sensorless Simultaneous Rotary-Translational Axis Motion Error Measurement and Trace Based on Virtual Bar

Volume 8: Dynamic Systems and Control, Parts A and B ◽

10.1115/imece2010-39947 ◽

2010 ◽

Author(s):

Yuqing Zhou ◽

Xuesong Mei ◽

Gedong Jiang ◽

Nuogang Sun ◽

Bai Shao

Keyword(s):

Mathematical Model ◽

Feature Extraction ◽

Wavelet Transform ◽

Machine Tool ◽

Error Measurement ◽

Error Source ◽

Spatial Error ◽

Motion Error ◽

Circular Test ◽

The Mathematical Model

Simultaneous rotary-translational (R-T) axis motion error has significant influence on multi-axis machine tool precision. To improve multi-axis machine tool precision, axis motion error measurement and trace method are investigated in this study. A sensorless R-T axis motion error measurement and trace technology based on virtual bar is proposed. Firstly, the fundamental sensorless test principle is discussed. Then, the virtual-bar-based test path of a circular test though a rotary axis and two translational axes motion is scheduled. The mathematical model of motion error is established. Furthermore, to identify the error source, spatial error charts and some advanced signal processing and feature extraction technologies, such as wavelet transform and frequency analysis, are used. The analysis of experimental results shows that it is practical and efficient to use the virtual bar and the sensorless information to estimate motion error.

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A Method of Using Neural Networks and Inverse Kinematics for Machine Tools Error Estimation and Correction

Journal of Manufacturing Science and Engineering ◽

10.1115/1.2831101 ◽

1997 ◽

Vol 119 (2) ◽

pp. 247-254 ◽

Cited By ~ 28

Author(s):

J. Mou

Keyword(s):

Neural Network ◽

Neural Networks ◽

Machine Tool ◽

Inverse Kinematics ◽

Network Models ◽

Thermal Conditions ◽

Depth Of Cut ◽

Time Varying ◽

Neural Network Models ◽

Cutting Processes

A method using artificial neural networks and inverse kinematics for machine tool error correction is presented. A generalized error model is derived, by using rigid body kinematics, to describe the error motion between the cutting tool and workpiece at discrete temperature conditions. Neural network models are then built to track the time-varying machine tool errors at various thermal conditions. The output of the neural network models can be used to periodically modify, using inverse kinematics technique, the error model’s coefficients as the cutting processes proceeded. Thus, the time-varying positioning errors at other points within the designated workspace can be estimated. Experimental results show that the time-varying machine tool errors can be estimated and corrected with desired accuracy. The estimated errors resulted from the proposed methodology could be used to adjust the depth of cut on the finish pass, or correct the probing data for process-intermittent inspection to improve the accuracy of workpieces.

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‘Open-loop’ tracking interferometer for machine tool volumetric error measurement—Two-dimensional case

Precision Engineering ◽

10.1016/j.precisioneng.2014.03.004 ◽

2014 ◽

Vol 38 (3) ◽

pp. 666-672 ◽

Cited By ~ 13

Author(s):

Soichi Ibaraki ◽

Goh Sato ◽

Kunitaka Takeuchi

Keyword(s):

Machine Tool ◽

Open Loop ◽

Dimensional Case ◽

Error Measurement ◽

Two Dimensional ◽

Volumetric Error ◽

Tracking Interferometer

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An On-Machine Error Measurement System for Micro-Machining

ASME 2007 International Manufacturing Science and Engineering Conference ◽

10.1115/msec2007-31053 ◽

2007 ◽

Cited By ~ 2

Author(s):

Shih-Ming Wang ◽

Han-Jen Yu ◽

Yi-Hung Liu ◽

Da-Fun Chen

Keyword(s):

Machine Tool ◽

Measurement System ◽

Error Compensation ◽

Model Comparison ◽

Contour Error ◽

Machining Accuracy ◽

Error Measurement ◽

Micro Machining ◽

Machine Error ◽

Machining Errors

Technology development trends towards the ability to manufacture ever smaller parts and feature sizes with increased precision and decreased cost. Micro machining is one of the important manufacturing methods to fulfill the requirements from the industry. The objective of this paper is to develop an on-machine error measurement system that can identify the micro machining errors for error compensation so that the machining accuracy of a meso-scale machine tool (mMT) can be enhanced. Because of the difficulty in handling and repositioning the miniature workpiece, the error measurement system should be non-contact and on-machine executable. To meet this requirement, a vision-based error measurement system integrating image re-constructive technology, camera pixel correction, and model comparison algorithm error was developed in this study. The proposed measurement system consists of a CCD with CCTV lens, a precision 3-DOF platform, image re-construction sub-system, and contour error calculation sub-system. By adopting Canny Edge Detection algorithm and camera pixel calibration method, the contour of a machined workpiece can be identified and compared to the pixel-based theoretical contour model of the workpiece to determine the micro machining errors. Because the system does not have to remove the machined workpiece from the CNC machine tool, errors due to re-installing and re-positioning can be avoided. To prove the feasibility of the developed algorithm and system, measurement results obtained from the vision-based measurement system were compared with the measurements of CMM, and error compensation experiment conducted on a 3-DOF mMT was also conducted. The results have shown the good feasibility and effectiveness of the developed system.

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Positioning Errors Measurement of CNC Machine Tools Based on J-DBB Method

Applied Sciences ◽

10.3390/app112411770 ◽

2021 ◽

Vol 11 (24) ◽

pp. 11770

Author(s):

Tao Sun ◽

Wen Wang ◽

Zhanfeng Chen ◽

Yewen Zhu ◽

Kaifei Xu ◽

...

Keyword(s):

Machine Tool ◽

Machine Tools ◽

Degree Of Freedom ◽

Ball Screw ◽

Cnc Machine Tools ◽

Positioning Error ◽

Cnc Machine Tool ◽

Spherical Joint ◽

Cnc Machine ◽

Positioning Errors

Due to the errors of the servo system and the errors of the ball screw drive system, the positioning errors inevitably occur in the process of CNC machine tools. The measurement of traditional equipment is limited by a fixed measurement radius and a single degree of freedom, which can only be measured within a fixed plane. In this paper, four different positioning errors of CNC machine tools are first measured at full scale by using J-DBB (a modified double ball bar with one spherical joint connecting two bars) method. The J-DBB device uses a three-degree-of-freedom spherical joint as a connecting part, which realizes that the measurement radius can be continuously changed, and the measurement space is a spatial sphere. First, the principle of the J-DBB method is briefly introduced. Next, four typical positioning errors of CNC machine tools are analyzed and examined, which contain the uniform contraction error of ball screw and linear grating, periodic error of the ball screw and linear grating, interference of measurement devices error, and opposite clearance error. In the end, the trajectories of the CNC machine tool spindle with a single positioning error are simulated by using the J-DBB method. The results reveal that this method can be used for the positioning error of machine tools, which helps to better understand the spatial distribution of CNC machine tool errors and provides guidance for the reasonable selection of working areas to improve the machining accuracy of parts.

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