Measuring and Modeling of Volumetric Errors for Vertical Machining Centers Based on Bi-Directional Laser Sequential Step Diagonal Measurement

2018 ◽  
Author(s):  
Huimin Li ◽  
Sitong Xiang ◽  
Ming Deng ◽  
Mengrui Zhu ◽  
Zhengchun Du ◽  
...  
Keyword(s):  
Experimental Tests ◽  
Measuring Method ◽  
Geometric Errors ◽  
Machine Accuracy ◽  
Volumetric Error ◽  
Positioning Errors ◽  
Machining Center ◽  
Direct Measurements ◽  
Volumetric Errors ◽  
Squareness Errors

This paper proposes a bi-directional laser sequential step diagonal measuring method for three-axis vertical machining centers. Different measure paths are particularly designed for positive and negative directions, and corresponding error decoupling models are established. Based on the laser measuring data along these bi-directional paths, 18 geometric errors can be identified simultaneously, including 6 angular errors, 3 positioning errors, 6 straightness errors and 3 squareness errors. Compared with single directional step diagonal measurements, the proposed bi-directional mothed is more efficient and can identify more error items, namely 6 angular errors. Experimental tests were conducted on a three-axis vertical machining center. Decoupled error items obtained by the proposed bi-direction measurements coincide with those from direct measurements via a laser Doppler displacement meter, which verified the feasibility of the proposed method. Finally, the position error of the machine whole workspace was predicted by building volumetric error model and the machine accuracy was improved.

Geometric Error Identification of a Three-Axis Machining Center

2013 ◽  
Vol 694-697 ◽  
pp. 1803-1807
Author(s):  
Gui Qiang Liang ◽  
Jun Xian Zhang ◽  
Fei Fei Zhao
Keyword(s):  
Working Conditions ◽  
Laser Interferometer ◽  
Great Influence ◽  
Geometric Error ◽  
Machining Accuracy ◽  
Geometric Errors ◽  
Positioning Errors ◽  
Machining Center ◽  
Influence Effect ◽  
Squareness Errors

Geometric errors of a machining center can cause great influence on machining accuracy, and these geometric errors should be identified and compensated in the actual working conditions. Taking a three-axis vertical machining center as example, 21 geometric errors of the machine tool were solved. By using the 12-line method based on a laser interferometer, identification principle of the positioning errors, straightness errors, pitch errors, yaw errors, roll errors and squareness errors are presented, and all of the 21 geometric errors of the machining center were identified. Geometric errors having great influence effect on machining accuracy can be identified. The research results provide guidance for analyze of geometric errors of machining center.

A Kinematic Model for Volumetric Error Estimation of a Special Purpose CNC Machine

2012 ◽  
Vol 232 ◽  
pp. 367-371 ◽  
Author(s):  
M. Simpson ◽  
I.A. Gorlach
Keyword(s):  
Error Estimation ◽  
Small Angle ◽  
Laser Interferometer ◽  
Kinematic Model ◽  
Error Reduction ◽  
Average Error ◽  
Cnc Machine ◽  
Volumetric Error ◽  
Direct Measurements ◽  
Volumetric Errors

This research reports on error identification and compensation of a special purpose CNC machine. The kinematic model of the machine was developed using rigid body kinematics and small angle approximation of the axes of the machine through homogenous transform matrices, and the equations describing the volumetric errors. The machine was calibrated to measure the axes errors, which were used in the kinematic model in order to determine compensation values. The model was evaluated by means of direct measurements of axis movements using a laser interferometer, as well as in cutting tests, where a large number of holes were drilled in plates and measured with a CMM. The results showed that the developed model achieved an average error reduction of 40%, for the X and Y axes.

DESIGN OF A 5-AXIS MACHINE TOOL CONSIDERING GEOMETRIC ERRORS

2010 ◽  
Vol 24 (15n16) ◽  
pp. 2484-2489 ◽  
Author(s):  
SUNG-RYUNG PARK ◽  
SEUNG-HAN YANG
Keyword(s):  
Machine Tool ◽  
High Precision ◽  
Design Parameter ◽  
Dynamic Environment ◽  
Geometric Errors ◽  
Volumetric Error ◽  
Critical Design ◽  
Precision Machine ◽  
Proposed Model ◽  
Squareness Errors

Control over scale, dynamic, environment, and geometric errors in 5-axis machine tool are required to realize a high precision machine tool. Especially geometric errors such as translational, rotational, offset, and squareness errors are important factors which should be considered in the design stages of the machine tool. In this paper, geometric errors are evaluated for different configurations of 5-axis machine tool, namely, 1) table tilting, 2) head tilting, and 3) universal and their error synthesis models are derived. The proposed model is different from the conventional error synthesis model since it considers offset and offset errors. The volumetric error is estimated for every configuration with random geometric errors. Finally, the best configuration, the critical design parameter and error are suggested.

Research on Geometric Errors Model and Identification of 5-Axis Machining Center for Processing Turbo Molecular Pump Rotor

2011 ◽  
Vol 211-212 ◽  
pp. 784-787
Author(s):  
Wu Zhao ◽  
Hao Ran Liu ◽  
Guo Ji Wang ◽  
Ling Bing Liu
Keyword(s):  
Physical Simulation ◽  
Geometric Errors ◽  
Volumetric Error ◽  
Pump Rotor ◽  
Transformation Matrices ◽  
Machine Performance ◽  
Machining Center ◽  
Volumetric Accuracy ◽  
Computationally Intensive ◽  
The Individual

This paper investigates the accuracy evaluative factors of 5-axis turbo molecular pump rotor machining center.Using rigid body kinematics techniques and homogenous transformation matrices, the systemic geometric volumetric error model are established for error synthesis. Novel volumetric accuracy model can be verified effectiveness better estimation of machine performance, by means of physical simulation and measurement. The effect of the individual axis geometric errors can become increasingly significant as the chain of dependent axis is extended. The effect of the rotary axis and their errors cannot be ignored. Calculating volumetric accuracy as the maximum difference between the error vector at any two positions can be computationally intensive.

Five-axis machine tool volumetric and geometric error reduction by indirect geometric calibration and lookup tables

2021 ◽  
pp. 1-25
Author(s):  
Sareh Esmaeili ◽  
René Mayer ◽  
Mark Sanders ◽  
Philipp Dahlem ◽  
Kanglin Xing
Keyword(s):  
Machine Tool ◽  
Experimental Tests ◽  
Cnc Machine Tools ◽  
Geometric Errors ◽  
Cnc Machine ◽  
Machine Error ◽  
Working Volume ◽  
Volumetric Errors ◽  
Lookup Tables ◽  
Five Axis

Abstract Modern CNC machine tools provide lookup tables to enhance the machine tool's precision but the generation of table entries can be a demanding task. In this paper, the coefficients of the 25 cubic polynomial functions used to generate the LUTs entries for a five-axis machine tool are obtained by solving a linear system incorporating a Vandermonde expansion of the nominal control jacobian. The necessary volumetric errors within the working volume are predicted from machine's geometric errors estimated by the indirect error identification method based on the on-machine touch probing measurement of a reconfigurable uncalibrated master ball artefact (RUMBA). The proposed scheme is applied to a small Mitsubishi M730 CNC machine. Two different error models are used for modeling the erroneous machine tool, one estimating mainly inter-axis errors and the other including numerous intra-axis errors. The table-based compensation is validated through additional on-machine measurements. Experimental tests demonstrate a significant reduction in volumetric errors and in the effective machine error parameters. The LUTs reduce most of the dominant machine error parameters. It is concluded that although being effective in correcting some geometric errors, the generated LUTs cannot compensate some axis misalignments such as EB(OX)A and EB(OX)Z. The Root Mean Square of the translational volumetric errors are improved from 87.3, 75.4 and 71.5 µm down to 24.8, 18.8 and 22.1 µm in the X, Y and Z directions, respectively.

scholarly journals Experimental Strain Measurement Approach Using Fiber Bragg Grating Sensors for Monitoring of Railway Switches and Crossings

Sensors ◽  
2021 ◽  
Vol 21 (11) ◽  
pp. 3639
Author(s):  
Abdelfateh Kerrouche ◽  
Taoufik Najeh ◽  
Pablo Jaen-Sola
Keyword(s):  
Fiber Bragg Grating ◽  
Experimental Tests ◽  
Cost Effective ◽  
Measuring Method ◽  
Bragg Grating ◽  
Railway Network ◽  
System Failures ◽  
Railway Infrastructure ◽  
Train Speed ◽  
And Control

Railway infrastructure plays a major role in providing the most cost-effective way to transport freight and passengers. The increase in train speed, traffic growth, heavier axles, and harsh environments make railway assets susceptible to degradation and failure. Railway switches and crossings (S&C) are a key element in any railway network, providing flexible traffic for trains to switch between tracks (through or turnout direction). S&C systems have complex structures, with many components, such as crossing parts, frogs, switchblades, and point machines. Many technologies (e.g., electrical, mechanical, and electronic devices) are used to operate and control S&C. These S&C systems are subject to failures and malfunctions that can cause delays, traffic disruptions, and even deadly accidents. Suitable field-based monitoring techniques to deal with fault detection in railway S&C systems are sought after. Wear is the major cause of S&C system failures. A novel measuring method to monitor excessive wear on the frog, as part of S&C, based on fiber Bragg grating (FBG) optical fiber sensors, is discussed in this paper. The developed solution is based on FBG sensors measuring the strain profile of the frog of S&C to determine wear size. A numerical model of a 3D prototype was developed through the finite element method, to define loading testing conditions, as well as for comparison with experimental tests. The sensors were examined under periodic and controlled loading tests. Results of this pilot study, based on simulation and laboratory tests, have shown a correlation for the static load. It was shown that the results of the experimental and the numerical studies were in good agreement.

Modeling and Identification of Geometric Error Based on Screw Theory

2014 ◽  
Vol 941-944 ◽  
pp. 2219-2223 ◽  
Author(s):  
Guo Juan Zhao ◽  
Lei Zhang ◽  
Shi Jun Ji ◽  
Xin Wang
Keyword(s):  
Machine Tool ◽  
Laser Interferometer ◽  
Screw Theory ◽  
Geometric Error ◽  
New Method ◽  
Geometric Errors ◽  
Volumetric Error ◽  
B Spline ◽  
The Individual

In this paper, a new method is presented for the identification of machine tool component errors. Firstly, the Non-Uniform Rational B-spline (NURBS) is established to represent the geometric component errors. The individual geometric errors of the motion parts are measured by laser interferometer. Then, the volumetric error for a machine tool with three motion parts is modeled based on the screw theory. Finally, the simulations and experiments are conducted to confirm the validity of the proposed method.

Development of a Ring Permeability Test System

2010 ◽  
Vol 136 ◽  
pp. 153-157
Author(s):  
Yu Hong Du ◽  
Xiu Ming Jiang ◽  
Xiu Ren Li
Keyword(s):  
Control System ◽  
Control Method ◽  
Dynamic Performance ◽  
Experimental Tests ◽  
Measuring Method ◽  
Test System ◽  
Fluid Theory ◽  
And Control ◽  
Relationship Of ◽  
The Mathematical Model

To solve the problem of detecting the permeability of the textile machinery, a dedicated test system has been developed based on the pressure difference measuring method. The established system has a number of advantages including simple, fast and accurate. The mathematical model of influencing factors for permeability is derived based on fluid theory, and the relationship of these parameters is achieved. Further investigations are directed towards the inherent characteristics of the control system. Based on the established model and measuring features, an information fusion based clustering control system is proposed to implement the measurement. Using this mechanical structure, a PID control system and a cluster control system have been developed. Simulation and experimental tests are carried out to examine the performance of the established system. It is noted that the clustering method has a high dynamic performance and control accuracy. This cluster fusion control method has been successfully utilized in powder metallurgy collar permeability testing.

Identification and Compensation of Geometric and Elastic Errors in Large Manipulators: Application to a High Accuracy Medical Robot

1998 ◽  
Author(s):  
Marco A. Meggiolaro ◽  
Constantinos Mavroidis ◽  
Steven Dubowsky
Keyword(s):  
High Accuracy ◽  
Measured Data ◽  
Experimental Results ◽  
Geometric Errors ◽  
Medical Robot ◽  
Error Sources ◽  
End Effector ◽  
Positioning Errors ◽  
Structural Deformations ◽  
Manufacturing Tolerances

Abstract A method is presented to identify the source of end-effector positioning errors in large manipulators using experimentally measured data. Both errors due to manufacturing tolerances and other geometric errors and elastic structural deformations are identified. These error sources are used to predict, and compensate for, the end-point errors as a function of configuration and measured forces. The method is applied to a new large high accuracy medical robot. Experimental results show that the method is able to effectively correct for the errors in the system.

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