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.

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.

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.

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.

Error Analysis by Square 3 x 3 Machining Method for Five-Axis Machining Centers

2020 ◽  
Author(s):  
Shigehiko Sakamoto ◽  
Atsushi Yokoyama ◽  
Kazumasa Nakayasu ◽  
Toshihiro Suzuki ◽  
Shinji Koike
Keyword(s):  
International Standards ◽  
Test Method ◽  
Accuracy Evaluation ◽  
Alignment Error ◽  
Machined Surface ◽  
Machining Center ◽  
Alignment Errors ◽  
Assembly Error ◽  
Five Axis ◽  
Machined Surfaces

Abstract The establishment of international standards for 5-axis control machining centers has been supported by the high interest of each country. Internationally, various accuracy inspection methods have been proposed and widely discussed. Accuracy measuring devices for these purposes have also been proposed. In 2014, inspection methods for 5-axis machines were published in ISO 10791-6 and 10791-7. In this research, we propose a test method to process 9 square faces as a new accuracy evaluation method. We simulate the influence of assembly error by the proposed square 3 × 3 machining method on the machined surface. By processing 9 square faces with different tool angle on the same plane, it was possible to evaluate the influence of assembly errors in the 5-axis machining center on the machined surface. Nine surfaces machined by the square 3 × 3 processing method cause differences in surface height due to alignment errors. In addition, nine machined surfaces become all diagonal not parallelism. The alignment errors of the 5-axis machining center is identified by evaluating the orientation of the machined surfaces. Specifically, we propose a newly method to measure the height difference of nine surfaces. Then, the possibility of identifying the alignment error of the 5-axis machining center using the measurement results is shown.

Geometric accuracy allocation for multi-axis CNC machine tools based on sensitivity analysis and reliability theory

2014 ◽  
Vol 229 (6) ◽  
pp. 1134-1149 ◽  
Author(s):  
Qiang Cheng ◽  
Ziling Zhang ◽  
Guojun Zhang ◽  
Peihua Gu ◽  
Ligang Cai
Keyword(s):  
Sensitivity Analysis ◽  
Machine Tool ◽  
Operating Conditions ◽  
Numerical Control ◽  
Cnc Machine Tools ◽  
Machining Accuracy ◽  
Geometric Errors ◽  
Volumetric Error ◽  
The Cost ◽  
Five Axis

Machining accuracy of a machine tool is influenced by geometric errors produced by each part and component. Different errors have varying influence on the machining accuracy of a tool. The aim of this study is to optimize errors to get a desired performance for a numerical control machine tool. Applying multi-body system theory, a volumetric error model was constructed to track and compensate effects of errors during operation of the machine, and to relate the functional specifications on volumetric accuracy to the permissible errors on the joints and links of the machine. Error sensitivity analysis was used to identify the influence of different errors (especially the errors which have large influences) on volumetric error. Based on First Order and Second Moment theory, an error allocation approach was developed to optimize allocation of manufacturing and assembly tolerances along with specifying the operating conditions to determine the optimal level of these errors so that the cost of controlling them and the cost of failure to meet the specifications is minimized. The approach developed was implemented in software and an example of the geometric errors budgeting for a five-axis machine was discussed. It is identified that the different optimal standard deviations reflect the cost-weighted influences of the respective parameters in the equations of the functional requirements. This study suggests that it is possible to determine the coupling relationships between these errors and optimize the allowable error budgeting between these sources.

Research of the Technological Parameters Influencing on the Surface Quality of Micro Complex Surface

2005 ◽  
Vol 291-292 ◽  
pp. 513-518 ◽  
Author(s):  
Ming Jun Chen ◽  
Ying Chun Liang ◽  
Ya Zhou Sun ◽  
W.X. Guo ◽  
Wen Jun Zong
Keyword(s):  
Machine Tool ◽  
Three Dimensional ◽  
Complex Surface ◽  
Cutting Parameters ◽  
Numerical Control ◽  
Tool Geometry ◽  
Machining Accuracy ◽  
Technological Parameters ◽  
Machined Surface ◽  
Machining Errors

In order to machine complex free surface parts, a micro NC (numerical control) three-dimensional machine tool is developed, integrated the PMAC control. Based on this NC machine tool, the influencing of the technological and tool’s parameters on machining accuracy of micro complex surface parts are analyzed, and the cause to lead to the machining errors is explained. Therefore, the cutting parameters and tool geometry parameters to machine micro complex surface, such as the human’s face, can be selected optimally. Finally, the micro complex human’s face is machined on this developed micro machine tool under optimal parameters. The experimental results show that the machined surface is smooth and continuous. The machined quality is satisfied.

scholarly journals Kinematic Analysis and Parameter Measurement for Multi-Axis Laser Engraving Machine Tools

Machines ◽  
2021 ◽  
Vol 9 (10) ◽  
pp. 237
Author(s):  
Zhenshuo Yin ◽  
Qiang Liu ◽  
Pengpeng Sun ◽  
Ji Ding
Keyword(s):  
Coordinate System ◽  
Machine Tools ◽  
Measurement Method ◽  
Kinematic Model ◽  
Complex Surface ◽  
Parameter Measurement ◽  
Contour Error ◽  
Unknown Parameters ◽  
Laser Engraving ◽  
Tool Motion

Multi-axis Laser Engraving Machine Tools (LEMT) are widely used in precision processing of parts with complex surface. The accuracy of kinematic model and parameter measurement are the key factors determining the processing quality of LEMT. In this paper, a kinematic model of multi-axis LEMT was established based on Homogeneous Transformation Matrix (HTM). Two types of unknown parameters, linkage parameters and positioning parameters, were measured in the presented model. Taking advantage of the characteristics of laser processing, this paper proposed a rapid measurement method of linkage parameters by combining the machine tool motion with the laser marking action. For positioning parameters, this study proposed a non-contact measurement method based on structured light scanner, which can obtain the translation values and the rotation values from the Workpiece Coordinate System (WCS) to the Basic Coordinate System (BCS) simultaneously. After the measurement of two kinds of parameters of a multi-axis LEMT was completed, the processing of a spatial curve was performed and the average contour error was controlled at 15.1 µm, which is sufficient to meet the project requirements.

Proposal of a Machining Test of Five-Axis Machining Centers Using a Truncated Square Pyramid

2012 ◽  
Vol 523-524 ◽  
pp. 475-480 ◽  
Author(s):  
Katsunori Ohta ◽  
Zhi Meng Li ◽  
Masaomi Tsutsumi
Keyword(s):  
Linear Interpolation ◽  
Test Method ◽  
Rotary Table ◽  
Evaluation Standard ◽  
Machining Center ◽  
Geometric Deviations ◽  
Machining Test ◽  
Simulation And Experiment ◽  
Universal Spindle ◽  
Five Axis

NAS 979 has been used for over 40 years as a performance evaluation standard for five-axis machining centers. This standard provides some finishing conditions of the cone-frustum under five-axis control, and prescribes the measuring methods and permissible tolerances of geometric deviations. However, this standard cannot be applied to the tilting rotary table type five-axis machining center but to the universal spindle head type one. When the standard is applied to the tilting rotary table type, it is not clear yet that the effects of the geometric and synchronous deviations which influence the measured results. Thus, there are no methods for evaluating the accuracy of linear interpolation movement under simultaneous five-axis control. This paper proposes a machining test method using a truncated square pyramid for checking the accuracy of the tilting rotary table type five-axis machining centers. In the simulation and experiment, the bottom of the truncated square pyramid with a half apex angle of 15° is mounted on a fixture with a slope of 10° or 20°, and feed velocity of each axis is analyzed by changing the center position.

Influence of NC Control System on S-shaped Machining Accuracy of Five-axis Machining Center

2018 ◽  
Vol 2018 (0) ◽  
pp. S1310003
Author(s):  
Zongze LI ◽  
Ryuta SATO ◽  
Keiichi SHIRASE ◽  
Yukitoshi IHARA
Keyword(s):  
Control System ◽  
Machining Accuracy ◽  
Machining Center ◽  
Five Axis
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