Comparison of Relative Contributions of Process and Geometric Errors in Micro and Macro Scale Milling Using an Integrated Error Model

2009 ◽  
Author(s):  
George Mathai ◽  
Mukund Kumar ◽  
Shreyes Melkote ◽  
F. C. Hsu ◽  
C. C. Chiu ◽  
...  
Keyword(s):  
Machine Tool ◽  
Error Model ◽  
Geometric Errors ◽  
Relative Importance ◽  
Dimensional Error ◽  
Error Sources ◽  
Micro Scale ◽  
Relative Contribution ◽  
Thermal Growth ◽  
Macro Scale

Error models are available for individual error sources for specific components in a machine tool. However, proper error budgeting requires an understanding of the relative importance of various error sources. This paper presents an analysis of the relative contribution of process and geometric errors on the dimensional error produced in micro scale milling. The error contributions at the micro scale are compared and contrasted with those in macro scale milling. The analysis makes use of an error model that uses homogeneous transformation matrices (HTMs) to model the effect of each error source in each component of the machine tool on the final position of the tool with respect to the workpiece. The model is developed for a generic milling machine and used to compare the relative importance of errors due to misalignment, thermal growth, tool deflection and wear of the tool on the size of the machined feature at the micro and macro scale for slot milling using standard length tools.

scholarly journals Study on Telescope Gain Affected by a Multilevel Hybrid Mechanism in FAST

2014 ◽  
Vol 6 ◽  
pp. 841526 ◽  
Author(s):  
Xiaoming Chai ◽  
Jin Fan ◽  
Lanchuan Zhou ◽  
Bo Peng
Keyword(s):  
Radio Telescope ◽  
Physical Meaning ◽  
Error Model ◽  
Geometric Errors ◽  
Accuracy Analysis ◽  
Positioning Error ◽  
Error Sources ◽  
Positioning Accuracy ◽  
Hybrid Mechanism ◽  
Structural Deformations

This paper focuses on the telescope gain affected by a multilevel hybrid mechanism for the feed positioning in the five-hundred-meter aperture spherical radio telescope (FAST) project, which is based on the positioning accuracy analysis of the mechanism. First, error model for the whole mechanism is established and its physical meaning is clearly explained. Then two kinds of error sources are mainly considered: geometric errors and structural deformations. The positioning error over the mechanism's workspace is described by an efficient and intuitive approach. As the feed position error will lower the telescope gain, this influence is analyzed in detail. In the end, it is concluded that the design of the mechanism can meet the requirement of the telescope performance.

The Research on the Orientation Error of Three-Axis Turntable in Theory and Measuring Method Based on Assembling

2006 ◽  
Vol 532-533 ◽  
pp. 849-852
Author(s):  
Yan Li ◽  
Da Peng Fan
Keyword(s):  
Machine Tool ◽  
Measuring Method ◽  
Error Model ◽  
Geometric Errors ◽  
Body System ◽  
Orientation Error ◽  
Nc Machine Tool ◽  
Nc Machine ◽  
Multi Body

Based on the analysis of geometric errors of mechanism assembling, this paper applies the multi-body system kinematics theory in building the orientation error model of three-axis turntable induced by assembling errors. The results using the model could be easily applied in controlling turntable by error’s compensation, and shows which assembling error item has the larger effect. Furthermore，referenced by the measuring means of three-axis turntable, this paper conceives the definitions of the volumetric and orientation accuracy aimed at the turntable system, enlightened from the conception of NC machine tool. This research may be helpful to the foundation of the systematic conception of the turntable accuracy no matter in theory or in measuring method.

A Part Error Model Considering the Machine Tool Positioning Errors and Process-Induced Errors

2009 ◽  
Author(s):  
Y. Y. Liao ◽  
H. N. Chiang ◽  
J. J. Wang ◽  
F. C. Hsu ◽  
C. F. Wu ◽  
...  
Keyword(s):  
Machine Tool ◽  
Milling Process ◽  
Error Model ◽  
Machining Process ◽  
Dispersion Property ◽  
Positioning Error ◽  
Dimensional Error ◽  
Spatial Error ◽  
Tool Positioning ◽  
Positioning Errors

Parts geometrical and dimensional error for a machining process can be attributed to several factors, including tool wear, thermal deformation, the machine tool positioning error and force-induced process error. Although the latter two factors are often more significant, their effect on the parts accuracy is more elusive and difficult to predict due to their inherent statistical dispersion property. It is therefore the subject of this investigation to quantitatively relate the parts error to machine tool spatial error and process-induced errors. Through root mean square calculation, a part error model is established by combining the machine tool positioning error, work vibration and tool vibration. The part error model considers two ranges of surface error consisting of surface roughness and cutting depth error of a machined plate. Using milling process as an example, the part error is predicted and compared with measurement result. The validity of this model is verified through a series of milling experiments under various cutting conditions.

Accuracy Calibration of 5-Axis Machine Tool Based on a Laser Approach

2012 ◽  
Vol 263-266 ◽  
pp. 680-685
Author(s):  
Fang Yu Pan ◽  
Jian Yin ◽  
Ming Li
Keyword(s):  
Machine Tool ◽  
Cutting Tool ◽  
Error Model ◽  
Geometric Errors ◽  
Machining Precision ◽  
The Relationship

To improve the machining precision and reduce the geometric errors for 5-axis machine tool, error model and calibration are presented in this paper. Error model is realized by Denavit-Hartenberg matrixes and homogeneous transformations, which can establish the relationship between the cutting tool and the workpiece. The accuracy calibration was difficult to achieve, but by a laser approach, the errors can be displayed accurately which is benefit for later compensation.

Interpolation and Extrapolation of Optimally-Fitted Kinematic Error Model for Five-Axis Machine Tools

2021 ◽  
pp. 1-25
Author(s):  
Le Ma ◽  
Douglas Bristow ◽  
Robert Landers
Keyword(s):  
Machine Tool ◽  
Interpolation Space ◽  
Geometric Error ◽  
Error Model ◽  
Geometric Errors ◽  
Model Errors ◽  
Volumetric Error ◽  
Extrapolation Space ◽  
The Mean ◽  
Five Axis

Abstract Machine tool geometric errors are frequently corrected by populating compensation tables that contain position-dependent offsets to each commanded axis position. While each offset can be determined by directly measuring the individual geometric error at that location, it is often more efficient to compute the compensation using a volumetric error model derived from measurements across the entire workspace. However, interpolation and extrapolation of measurements, once explicit in direct measurement methods, become implicit and obfuscated in the curve fitting process of volumetric error methods. The drive to maximize model accuracy while minimizing measurement sets can lead to significant model errors in workspace regions at or beyond the range of the metrology equipment. In this paper, a novel method of constructing machine tool volumetric error models is presented in which the characteristics of the interpolation and extrapolation errors are constrained. Using a typical five-axis machine tool compensation methodology, a constraint bounding the tool tip modeled error slope is added to the error model identification process. By including this constraint over the entire space, the geometric errors over the interpolation space are still well-identified. Also, the model performance over the extrapolation space is consistent with the behavior of the geometric error model over the interpolation space. The methodology is applied to an industrial five-axis machine tool. In the experimental implementation, for measurements outside of the measured region, an unconstrained model increases the mean residual by 40% while the constrained model reduces the mean residual by 40%.

scholarly journals 2D-wavelet based micro and macro texture analysis for asphalt pavement under snow or ice condition

2021 ◽  
Vol 2 (1) ◽  
Author(s):  
Feng Li ◽  
Gulnigar Ablat ◽  
Siqi Zhou ◽  
Yixin Liu ◽  
Yufeng Bi ◽  
...  
Keyword(s):  
Wavelet Transform ◽  
Asphalt Pavement ◽  
Asphalt Mixture ◽  
Micro Scale ◽  
Braking System ◽  
Macro Scale ◽  
Texture Characteristics ◽  
The Mean ◽  
Resistance Performance

AbstractIn ice and snow weather, the surface texture characteristics of asphalt pavement change, which will significantly affect the skid resistance performance of asphalt pavement. In this study, five asphalt mixture types of AC-5, AC-13, AC-16, SMA-13, SMA-16 were prepared under three conditions of the original state, ice and snow. In this paper, a 2D-wavelet transform approach is proposed to characterize the micro and macro texture of pavement. The Normalized Energy (NE) is proposed to describe the pavement texture quantitatively. Compared with the mean texture depth (MTD), NE has the advantages of full coverage, full automation and wide analytical scale. The results show that snow increases the micro-scale texture because of its fluffiness, while the formation of the ice sheets on the surface reduces the micro-scale texture. The filling effect of snow and ice reduces the macro-scale texture of the pavement surface. In a follow-up study, the 2D-wavelet transform approach can be applied to improve the intelligent driving braking system, which can provide pavement texture information for the safe braking strategy of driverless vehicles.

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