Influence of NC Program Quality and Geometric Errors Onto S-Shape Machining Accuracy

2018 ◽  
Author(s):  
Ryuta Sato ◽  
Keiichi Shirase ◽  
Yukitoshi Ihara
Keyword(s):  
Great Influence ◽  
Geometric Error ◽  
Machining Accuracy ◽  
Geometric Errors ◽  
Machined Surface ◽  
Nc Program ◽  
Finished Surface ◽  
Machining Test ◽  
Five Axis

S-shaped machining test is proposed for ISO standard to evaluate the motion accuracy of five-axis machining centers. However, it have not been investigated that which factor mainly influences the quality of the finished S-shape workpieces. This study focuses on the influence of the quality of NC program and geometric errors of rotary axes onto the quality of finished surface. Actual cutting tests and simulations are carried out to the investigation. As the results, it is clarified that the tolerance of NC program has a great influence onto the quality. It is also clarified that the geometric errors have great influences onto the quality. However, it is difficult to evaluate the influence of each geometric error because all geometric errors make glitches at the same point on the machined surface. It can be concluded that the proposed S-shape machining test can be used as the total demonstration of the machining techniques.

scholarly journals Prediction of machining accuracy based on geometric error estimation of tool rotation profile in five-axis multi-layer flank milling process

2020 ◽  
Vol 234 (11) ◽  
pp. 2160-2177
Author(s):  
Hangzhuo Yu ◽  
Lei Jiang ◽  
Jindong Wang ◽  
Shengfeng Qin ◽  
Guofu Ding
Keyword(s):  
Prediction Model ◽  
Great Influence ◽  
Milling Process ◽  
Geometric Error ◽  
Flank Milling ◽  
Machining Accuracy ◽  
Machined Surface ◽  
Contact Points ◽  
Five Axis ◽  
Tool Rotation

In five-axis multi-layer flank milling process, the geometric error of tool rotation profile caused by radial dimension error and setup error has great influence on the machining accuracy. In this work, a new comprehensive error prediction model considering the inter-layer interference caused by tool rotation profile error is established, which incorporates a pre-existing prediction model dealing with a variety of errors such as geometric errors of machine tool, workpiece locating errors, and spindle thermal deflection errors. First, a series of tool contact points on the tool swept surface in each single layer without overlapping with others are calculated. Second, the position of the tool contact points on the overlapped layers is updated based on the detection and calculation of inter-layer interferences. Third, all evaluated tool contact points on the final machined surface are available for completing the accuracy prediction of the machined surface. A machining experiment has been carried out to validate this prediction model and the results show the model is effective.

Sensitivity Analysis of Geometric Errors for Five-Axis CNC Machine Tool Based on Multi-Body System Theory

2012 ◽  
Vol 271-272 ◽  
pp. 493-497
Author(s):  
Wei Qing Wang ◽  
Huan Qin Wu
Keyword(s):  
System Theory ◽  
Sensitivity Analysis ◽  
Machine Tool ◽  
Geometric Error ◽  
Machining Accuracy ◽  
Geometric Errors ◽  
Body System ◽  
Cnc Machine ◽  
Multi Body ◽  
Five Axis

Abstract: In order to determine that the effect of geometric error to the machining accuracy is an important premise for the error compensation, a sensitivity analysis method of geometric error is presented based on multi-body system theory in this paper. An accuracy model of five-axis machine tool is established based on multi-body system theory, and with 37 geometric errors obtained through experimental verification, key error sources affecting the machining accuracy are finally identified by sensitivity analysis. The analysis result shows that the presented method can identify the important geometric errors having large influence on volumetric error of machine tool and is of help to improve the accuracy of machine tool economically.

The Effect of Geometric Error on Machining Accuracy for Machining Center

2013 ◽  
Vol 690-693 ◽  
pp. 3244-3248
Author(s):  
Gui Qiang Liang ◽  
Ai Rong Zhang ◽  
Ting Ting Guo
Keyword(s):  
Great Influence ◽  
Geometric Error ◽  
Linear Displacement ◽  
Machining Accuracy ◽  
Geometric Errors ◽  
Lower Body ◽  
Body System ◽  
Research Results ◽  
Machining Center ◽  
Multi Body

In order to improve machining accuracy of machining center, the effect of geometric error on machining accuracy was researched by multi-body system theory. Taking a vertical machining center as example, topological structure of the machining center was described by lower body array. Geometric errors of the bodies in the multi-body system were expressed by homogeneous coordinate transformation. Error model for machining accuracy was deduced and geometric errors having great influence on the machining accuracy were identified. The research results show that, straightness errors and linear displacement errors in three directions have direct influence on machining accuracy, and the effect on machining accuracy caused by angle errors are related to the dimensions of the machining center and travel distance of the three axes. The research results provide guidance for analysis on sensitivity of geometric errors.

To Identify Key Geometric Errors of 3-Axis NC Machine Tool by Machining Accuracy Failure Mode Analysis

2019 ◽  
Author(s):  
Baobao Qi ◽  
Qiang Cheng ◽  
Zhifeng Liu ◽  
Dongyang Sun
Keyword(s):  
Machine Tool ◽  
Failure Mode ◽  
Failure Modes ◽  
Geometric Error ◽  
Mode Analysis ◽  
Major Influence ◽  
Work Piece ◽  
Machining Accuracy ◽  
Geometric Errors ◽  
Machined Surface

Abstract Machine tools usually cut two or more surfaces after the work piece clamped on work table. In order to improve the machining accuracy and optimize accuracy design, it is hoped that the geometric errors that influence the accuracy of machined surface prominently can be known beforehand, so the adjustment will be carried out with a definite objective rather than without any clue. Because the machining accuracy of each direction in 3-D space is different value, in this paper, machining accuracy failure mode was defined as the various combination of the machining accuracy of each direction according to whether it is up to the reserved objective value or not. A three-axis machine tool was selected as an example and there were 7 machining accuracy failure modes for it. Based on the generalized correlation analysis, the correlation relationships between 7 machining accuracy failure modes were analyzed, and the main failure modes that affect the machining accuracy of work piece to be machined were identified. For each machining accuracy failure mode, key geometric error that had major influence on it was identified based on sensitivity analysis. Finally, four stepped work pieces were milled by a 3-axis machine tool to illustrate the analytical method proposed in this study.

Sensitivity Analysis Between Error Motions and Machined Shape Errors in Five-Axis Machining Centers: In Case of S-Shaped Machining Test by a Square End Mill

2019 ◽  
Author(s):  
Zongze Li ◽  
Ryuta Sato ◽  
Keiichi Shirase ◽  
Yukitoshi Ihara
Keyword(s):  
Sensitivity Analysis ◽  
Coordinate System ◽  
Complex Surface ◽  
Machining Accuracy ◽  
Machined Surface ◽  
Machining Center ◽  
Shape Errors ◽  
Machining Test ◽  
Tool Motion ◽  
Five Axis

Abstract Five-axis machining center, combined three linear and two rotary axes, has been increasingly used in complex surface machining. However, as the two additional axes, the machined surface under table coordinate system is usually different from the tool motion under machine coordinate system, and as a result, it is very tough to predict the machined shape errors caused by each axes error motions. This research presents a new kind of sensitivity analysis method, to find the relationship between error motions of each axis and geometric errors of machined shape directly. In this research, the S-shaped machining test is taken as a sample to explain how the sensitivity analysis makes sense. The results show that the presented sensitivity analysis can investigate how the error motions affect the S-shaped machining accuracy and predicted the influence of error motions on certain positions, such as the reversal errors of the axes around motion reversal points. It can be proved that the presented method can help the five-axis machining center users to predict the machining errors on the designed surface of each axes error motions.

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.

Geometric Errors Sensitivity Analysis of Precision Vertical Machining Center Based on Multi-Body System Theory

2011 ◽  
Vol 108 ◽  
pp. 61-66 ◽  
Author(s):  
Qiang Cheng ◽  
Dong Sheng Xuan ◽  
Jie Sun ◽  
Zhi Feng Liu
Keyword(s):  
System Theory ◽  
Sensitivity Analysis ◽  
Machine Tool ◽  
Great Influence ◽  
Geometric Error ◽  
Machining Accuracy ◽  
Geometric Errors ◽  
Body System ◽  
Machining Center ◽  
Multi Body

Parts of geometric error coupled into space error is the main reason that affects machining accuracy of machine tools; therefore, how to determine the effect of geometric error to the machining accuracy and then assigning geometry precision of parts economically is a difficult problem in machine tool designing process. Therefore, based on multi-body system theory, a sensitivity analysis method of geometric error is put forward in this paper. Let’s take precision vertical machining center for an example. Firstly, an accuracy model of machining center is established based on multi-body system theory, and with 21 geometric errors obtained through experimental verification, key error sources affecting the machining accuracy are finally identified by sensitivity analysis. The example analysis shows that the proposed method can effectively identify the main geometric errors of parts that have great influence on volumetric error of machine tool, and thus provides important theoretical basis to improve the accuracy of machine tool economically.

Table-Based Volumetric Error Compensation of Large Five-Axis Machine Tools

2016 ◽  
Vol 139 (2) ◽  
Author(s):  
Jennifer Creamer ◽  
Patrick M. Sammons ◽  
Douglas A. Bristow ◽  
Robert G. Landers ◽  
Philip L. Freeman ◽  
...  
Keyword(s):  
Machine Tool ◽  
Error Compensation ◽  
Machine Tools ◽  
Data Gathering ◽  
Measurement Data ◽  
Geometric Error ◽  
Compensation Method ◽  
Geometric Errors ◽  
Simultaneous Generation ◽  
Five Axis

This paper presents a geometric error compensation method for large five-axis machine tools. Compared to smaller machine tools, the longer axis travels and bigger structures of a large machine tool make them more susceptible to complicated, position-dependent geometric errors. The compensation method presented in this paper uses tool tip measurements recorded throughout the axis space to construct an explicit model of a machine tool's geometric errors from which a corresponding set of compensation tables are constructed. The measurements are taken using a laser tracker, permitting rapid error data gathering at most locations in the axis space. Two position-dependent geometric error models are considered in this paper. The first model utilizes a six degree-of-freedom kinematic error description at each axis. The second model is motivated by the structure of table compensation solutions and describes geometric errors as small perturbations to the axis commands. The parameters of both models are identified from the measurement data using a maximum likelihood estimator. Compensation tables are generated by projecting the error model onto the compensation space created by the compensation tables available in the machine tool controller. The first model provides a more intuitive accounting of simple geometric errors than the second; however, it also increases the complexity of projecting the errors onto compensation tables. Experimental results on a commercial five-axis machine tool are presented and analyzed. Despite significant differences in the machine tool error descriptions, both methods produce similar results, within the repeatability of the machine tool. Reasons for this result are discussed. Analysis of the models and compensation tables reveals significant complicated, and unexpected kinematic behavior in the experimental machine tool. A particular strength of the proposed methodology is the simultaneous generation of a complete set of compensation tables that accurately captures complicated kinematic errors independent of whether they arise from expected and unexpected sources.

Sensitivity Analysis of Error Motions and Geometric Errors in the Case of Sphere-Shaped Workpiece

2020 ◽  
Author(s):  
Zongze Li ◽  
Ryuta Sato ◽  
Keiichi Shirase
Keyword(s):  
Sensitivity Analysis ◽  
Machine Tools ◽  
End Milling ◽  
Geometric Errors ◽  
Machined Surface ◽  
Error Sources ◽  
Motion Error ◽  
Machining Center ◽  
Machining Errors ◽  
Five Axis

Abstract Motion error of machine tool feed axes influences the machined workpiece accuracy. However, the influences of each error sources are not identical; some errors do not influence the machined surface although some error have significant influences. In addition, five-axis machine tools have more error source than conventional three-axis machine tools, and it is very tough to predict the geometric errors of the machined surface. This study proposes a method to analyze the relationships between the each error sources and the error of the machined surface. In this study, a kind of sphere-shaped workpiece is taken as a sample to explain how the sensitivity analysis makes sense in ball-end milling. The results show that the method can be applied for the axial errors, such as motion reversal errors, to make it clearer to obverse the extent of each errors. In addition, the results also show that the presented sensitivity analysis is useful to investigate that how the geometric errors influence the sphere surface accuracy. It can be proved that the presented method can help the five-axis machining center users to predict the machining errors on the designed surface of each axes error motions.

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