Proposal of a machining test to evaluate dynamic synchronization error of rotary and linear axes with reversal of rotation direction

2021 ◽  
pp. 1-16
Author(s):  
Qingzhao Li ◽  
Soichi Ibaraki ◽  
Wei Wang
Keyword(s):  
Machine Tool ◽  
Coordinate System ◽  
Numerical Control ◽  
Synchronization Error ◽  
Free Form ◽  
Contour Error ◽  
Surface Geometry ◽  
Rotation Direction ◽  
Machining Test ◽  
Five Axis

Abstract The five-axis machining of a free-form surface often contains the reversal of a rotary axis' rotation direction with linear axis synchronized with it. This paper proposes a machining test to quantitatively evaluate the influence of the reversal of rotation direction on the surface geometry. In the five-axis machining, the trajectory of tool position and orientation is firstly given in the workpiece coordinate system by the CAM (Computer-aided Manufacturing) software, and the CNC (Computerized Numerical Control) system converts it to the machine coordinate system to calculate command trajectories. This paper clarifies that the tool path smoothing in the machine coordinate system can potentially cause a large contour error because of the dynamic synchronization error of rotary and linear axes. Although some academic works in the literature presented the smoothing in the workpiece coordinate system, many commercial CNC systems still employ the smoothing in the machine coordinate system, partly because machine tool users or makers do not clearly see how significant this influence can be on the machining accuracy. The proposed machining test enables a user to quantitatively evaluate it. The machining experiment shows that the geometric error of the finished test piece was as large as 0.16 mm under the conventional smoothing in a commercial CNC system, which can be significantly larger than the influence of other typical geometric errors of a five-axis machine tool. This paper shows, by numerical simulation, that the smoothing in the workpiece coordinate system can completely eliminate this contour error.

Determination of Geometry-Based Errors for Interpolated Tool Paths in Five-Axis Surface Machining

2005 ◽  
Vol 127 (1) ◽  
pp. 60-67 ◽  
Author(s):  
O. Remus Tutunea-Fatan ◽  
Hsi-Yung Feng
Keyword(s):  
Tool Path ◽  
Kinematic Chain ◽  
Cnc Machining ◽  
Numerical Control ◽  
Free Form ◽  
Cnc Machine ◽  
Surface Geometry ◽  
Contact Points ◽  
Five Axis ◽  
Deviation Method

Five-axis computer numerical control (CNC) machining is characterized with a multitude of errors. Among them an important component comes from the computer-aided manufacturing software known as the geometry-based errors. A new and accurate method to determine these errors is presented in this paper as opposed to the conventional chordal deviation method. The present method allows establishing the exact linearly interpolated tool positions between two cutter contact points on a given tool path, based on the inverse kinematics analysis of the machine tool. A generic procedure has been developed to ensure wide applicability of the proposed method. Analytical derivation of the geometry-based errors provides insights regarding the origin of these errors and their affecting parameters. Due to the highly non-linear characteristics of the problem, analytical solutions can only be obtained for simple surface geometry. Numerical computation is able to determine the errors for general surface shapes but it would be difficult to uncover further insightful information from the calculated error values. Besides the local surface geometry, the configuration of the kinematic chain of the CNC machine has been found to be the primary factor controlling the resulting value and type of the geometry-based errors. Implementations with a typical complex free-form surface demonstrated that the conventional chordal deviation method was not reliable and could significantly underestimate the geometry-based errors.

Tool Path Planning and NC Generation of Tilted Plane Machining Features for Five-Axis Machining

2011 ◽  
Vol 697-698 ◽  
pp. 309-313 ◽  
Author(s):  
Chen Hua She ◽  
Yueh Hsun Tsai
Keyword(s):  
Machine Tool ◽  
Degrees Of Freedom ◽  
Tool Path ◽  
Simulation Software ◽  
Free Form ◽  
Parent Child Relationship ◽  
Machining Feature ◽  
Machining Errors ◽  
Tilted Plane ◽  
Five Axis

Designs of free-form surface products are becoming increasingly complex. In traditional three-axis machine tool machining, errors that are caused by repetitive positioning and the costs of fixture jig design and manufacturing are critical. Since multi-axis machining provides two more rotational degrees of freedom than a three-axis machine tool, the former can solve these problems, and has therefore become the trend of precision cutting. As multi-axis machined parts often have holes and grooves on the tilted plane, this work proposes a method for machining tilted working plane features and for NC generation on a five-axis machine. The developed module can provide common geometric features, allowing the user to alter the machining feature and sequence on the tilted plane quickly using the parent-child relationship in a tree diagram, and plan the tool path. The postprocessor module developed in this paper can transform the tool path into an NC program required for machining. Finally, solid cutting simulation software is utilized to confirm the feasibility and correctness of the tool path and NC data of the tilted plane machining feature.

Toolpath Planning and Simulation for Cutting Test of Non-Orthogonal Five-Axis Machine Tool

2014 ◽  
Vol 625 ◽  
pp. 402-407
Author(s):  
Jeng Nan Lee ◽  
Chen Hua She ◽  
Chyouh Wu Brian Huang ◽  
Hung Shyong Chen ◽  
Huang Kuang Kung
Keyword(s):  
Machine Tool ◽  
Simulation Software ◽  
Nc Code ◽  
Location Data ◽  
Toolpath Planning ◽  
Cutting Test ◽  
Cad Cam ◽  
Machining Test ◽  
Universal Spindle ◽  
Five Axis

Owing to NAS 979 describes a cutting test for five-axis machine center with a universal spindle, several conditions for C-type machine tool have not been defined yet. This paper proposes a cutting test for a non-orthogonal swivel head and a rotary table type five-axis machine tool (C type) to evaluate its performance. The workpiece consists of 10 machining features. These features include the multi-axis simultaneous machining patterns and the positioning machining patterns. The flat end mill cutters are applied in each machining feature. Cutter location data for the test piece was generated using a commercial CAD/CAM system (UG) and converted to five-axis NC code using a postprocessor created in UG Post Builder. This UG postprocessor is verified through the developed postprocessor utilizing the modified D-H notation. It is also verified using VERICUT® solid cutting simulation software demonstrated the veracity of the generated five-axis NC code. The machining test is applicable for a variety of five-axis machine tool configurations.

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.

An Algorithm for Space Tool Compensation Used in Five-Axis Numerical Control System

2011 ◽  
Vol 141 ◽  
pp. 186-190
Author(s):  
Liang Zhao ◽  
Jing Chuan Dong ◽  
Zhi Feng Qiao ◽  
Yan Yu Ding ◽  
Zhi Yuan Tang
Keyword(s):  
Coordinate System ◽  
Local Coordinate System ◽  
Numerical Control ◽  
System Transformation ◽  
Cnc Machines ◽  
Surface Machining ◽  
New Space ◽  
Tool Compensation ◽  
And Function ◽  
Five Axis

This paper presents a new space cutter compensation algorithm used in five-axis CNC machines. Five-axis CNC machines are composed of three linear axes and two rotational axes, owing to its unique structure and function, especially it is adapted to free surface machining, and is used in mold, aviation and ship manufacture widely. This paper analyzes cutter’s feed path, creates a local coordinate system in the CC point by using transformation equation between CL point and CC point. In this local coordinate system cutter compensation is built, new CL point and new cutter angle is calculated. Through coordinate system transformation matrix, determine cutter absolute coordinate.

scholarly journals A geometric error tracing method based on the Monte Carlo theory of the five-axis gantry machining center

2017 ◽  
Vol 9 (7) ◽  
pp. 168781401770764 ◽  
Author(s):  
Jinwei Fan ◽  
Yuhang Tang ◽  
Dongju Chen ◽  
Changjun Wu
Keyword(s):  
Monte Carlo ◽  
Machine Tool ◽  
Test Piece ◽  
Great Influence ◽  
Numerical Control ◽  
Geometric Errors ◽  
Machining Center ◽  
Machining Errors ◽  
Five Axis ◽  
Tracing Method

This article proposes a tracing method to identify key geometric errors for a computer numerical control machine tool by cutting an S-shaped test piece. Adjacent part relationships and machine tool errors transform relationships are described by topology of the machining center. Global sensitivity analysis method based on quasi-Monte Carlo was used to analyze machining errors. Using this method, key geometric errors with significant influence on machining errors were obtained. Compensation of the key errors was used to experimentally improve machining errors for the S-shaped test piece. This method fundamentally determines the inherent connection and influence between geometric errors and machining errors. Key geometric errors that have great influence on machining errors can be determined quickly with this method. Thus, the proposed tracing method could provide effective guidance for the design and use of machine tools.

scholarly journals Effect of CAD/CAM Post Process on S-Shaped Machining Test for Five-Axis Machining Center

2019 ◽  
Vol 13 (5) ◽  
pp. 593-601
Author(s):  
Yukitoshi Ihara ◽  
Koichiro Takubo ◽  
Tatsuo Nakai ◽  
Ryuta Sato ◽  
◽  
...  
Keyword(s):  
Three Dimensional ◽  
Test Method ◽  
Rotation Direction ◽  
Post Process ◽  
Accuracy Test ◽  
Nc Program ◽  
Cad Cam ◽  
Machining Test ◽  
Three Dimensional Models ◽  
Five Axis

ISO 10791-7, the test standard for machining centers, was revised in 2014 to add the test method for five-axis machining centers. However, an S-shaped test was additionally proposed as an accuracy test of aircraft parts from China immediately before the establishment of the test standard. In an ISO meeting, various problems such as creating three-dimensional models and evaluation items have been indicated for the proposed test method. By revising these problems, the standard was finally completed and will be introduced as an informative annex soon. However, it is still an inappropriate test method from the viewpoint of performance inspection for machine tools. In this research, the S-shaped test method draft proposed in September 2016 is tested using two types of five-axis machining centers and commercial CAM software. Consequently, a hidden problem is revealed, that is, an abrupt movement that affected the final result is added to the machine because the rotation direction of the rotary axes is not ideal. This is attributed to the performance of the CAM software’s post processor that converts from CL data to NC program. This study provides some insights into avoiding the problem and obtaining better test results.

scholarly journals Tool-Path Planning Method For Kinematics Optimization of Blade Machining On Five-Axis Machine Tool

2022 ◽  
Author(s):  
Zhongyang Lu ◽  
Xu Yang ◽  
Ji Zhao
Keyword(s):  
Path Planning ◽  
Machine Tool ◽  
Tool Path ◽  
Machining Process ◽  
Free Form ◽  
Traditional Methods ◽  
Machining Quality ◽  
Blade Machining ◽  
Kinematic Performance ◽  
Five Axis

Abstract Planning tool-paths on free-form surfaces is a widely discussed issue. However, traditional methods of generating paths capable of meeting all the requirements of blade machining remain challenging. In this study, a new iso-parametric path-planning strategy based on a novel parameterization method combined with the conformal transformation theory was proposed. The proposed method could adapt to the curvature characteristics of the blade surface, improving the kinematic performance of the machining process, reducing multi-axis coordinated motion control complexity, and improving machining quality. The proposed method was then compared with three traditional methods. The influence of the tool-path on the kinematic performance of the machine tool was quantitatively examined based on the kinematics models of two different machine tools. A large cutting depth milling experiment was conducted to verify that kinematics optimization could improve machining quality. The proposed method provides a more reasonable path-planning approach for blade machining on a five-axis machine tool, which is of great significance in reducing the cost of blade machining and the risks of blade failure. Moreover, it is of great significance for the large-scale automated production of blades.

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.

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