A Data-Driven Machining Error Analysis Method for Finish Machining of Assembly Interfaces of Large-Scale Components

2020 ◽  
Vol 143 (4) ◽  
Author(s):  
Wei Fan ◽  
Lianyu Zheng ◽  
Wei Ji ◽  
Xun Xu ◽  
Lihui Wang ◽  
...  
Keyword(s):  
Error Analysis ◽  
Large Scale ◽  
Tool Path ◽  
Cutting Parameters ◽  
Pso Algorithm ◽  
Data Driven ◽  
Machining Accuracy ◽  
Machining Error ◽  
Spatial Statistical Analysis ◽  
Machining Errors

Abstract To guarantee the final assembly quality of the large-scale components, the assembly interfaces of large components need to be finish-machined on site. Such assembly interfaces are often in low-stiffness structure and made of difficult-to-cut materials, which makes it hard to fulfill machining tolerance. To solve this issue, a data-driven adaptive machining error analysis and compensation method is proposed based on on-machine measurement. Within this context, an initial definite plane is fitted via an improved robust iterating least-squares plane-fitting method based on the spatial statistical analysis result of machining errors of the key measurement points. Then, the parameters of the definite plane are solved by a simulated annealing-particle swarm optimization (SA-PSO) algorithm to determine the optimal definite plane; it effectively decomposes the machining error into systematic error and process error. To reduce these errors, compensation methods, tool-path adjustment method, and an optimized group of cutting parameters are proposed. The proposed method is validated by a set of cutting tests of an assembly interface of a large-scale aircraft vertical tail. The results indicate that the machining errors are successfully separated, and each type of error has been reduced by the proposed method. A 0.017 mm machining accuracy of the wall-thickness of the assembly interface has been achieved, well fulfilling the requirement of 0.05 mm tolerance.

A Generic, Geometric Approach to Accurate Machining-Error Predictions for 3-Axis CNC Milling of Sculptured Surface Parts: Part I — Modeling and Formulation

2006 ◽  
Author(s):  
Zezhong C. Chen ◽  
Wei Cai
Keyword(s):  
Tool Path ◽  
Cutting Tool ◽  
Geometric Model ◽  
Research Work ◽  
Geometric Approach ◽  
Cnc Machining ◽  
Sculptured Surface ◽  
Machining Error ◽  
Machining Errors ◽  
Tool Surface

In CNC machining, machining errors are usually caused by some of the sources such as cutting tool deflection, cutting tool wear, machine tool vibration, improper coolant/lubrication, and negative thermal effect. To increase product accuracy, much research has been carried out on the prediction of machining errors. However, in milling of sculptured surface parts, due to their curved shapes, the geometries of cutting tools do not match the parts’ surfaces well if the tools cut along the tool paths on the surfaces in a point-to-point way. As a consequence, machining error is inevitable, even if there is no other source of error in ideal machining conditions. To predict machining errors caused by this tool-surface mismatch, several methods have been proposed. Some of them are simple, and some represent the geometry of machined surfaces using cutter-swept surfaces. But none of these methods is accurate and practical. In this research work, a generic, geometric approach to predicting machining errors caused by the tool-surface mismatch is proposed for 3-axis sculptured surface milling. First, a new geometric model of the furrow formed by an APT tool moving between two neighboring cutter contact (CC) points is built. Second, the mathematical formula of cutting circle envelopes is derived. Then an algorithm for calculating machining errors in each tool motion is provided. Finally, this new approach is applied to two practical parts for the accurate machining-error predictions, and these predictions are then compared to the inaccurate predictions made by two established methods to demonstrate the advantages of this approach. This approach can be used in tool path planning for high precision machining of sculptured surface parts.

Experimental study on cutting factors of multi-layer machining for large aerospace thin-walled structural parts

2021 ◽  
pp. 095440892110403
Author(s):  
Hangzhuo Yu ◽  
Han Zhong ◽  
Yong Chen ◽  
Lei Lin ◽  
Jing Shi ◽  
...  
Keyword(s):  
Coordinate System ◽  
Experimental Method ◽  
Cutting Parameters ◽  
Machining Process ◽  
Machining Error ◽  
Machining Errors ◽  
Inner Surface ◽  
Thin Walled ◽  
Optimal Cutting Parameters ◽  
Cutting Path

Large aerospace thin-walled structures will produce deformation and vibration in the machining process, which will cause machining error. In this paper, a cutting experimental method based on multi-layer machining is proposed to analyze the influence of cutting tool, cutting path, and cutting parameters on machining error in order to obtain the optimal cutting variables. Firstly, aiming at the situation that the inner surface of the workpiece deviates from the design basis, the laser scanning method is used to obtain the actual shape of the inner surface, and the method of feature alignment is designed to realize the unification of the measurement coordinate system and machining coordinate system. Secondly, a series of cutting experiments are used to obtain the machining errors of wall thickness under different cutting tools, cutting paths, and cutting parameters, and the variation of machining errors is analyzed. Thirdly, a machining error prediction model is established to realize the prediction of machining error, and the multi-objective optimization method is used to optimize the cutting parameters. Finally, a machining test was carried out to validate the proposed cutting experimental method and the optimal cutting parameters.

An Efficient, Accurate Approach to Representing Cutter-Swept Envelopes and Its Applications to Three-Axis Virtual Milling of Sculptured Surfaces

2008 ◽  
Vol 130 (3) ◽  
Author(s):  
Zezhong C. Chen ◽  
Wei Cai
Keyword(s):  
Tool Path ◽  
Basic Mechanism ◽  
Cnc Milling ◽  
Sculptured Surfaces ◽  
Machining Error ◽  
Tool Paths ◽  
Virtual Machining ◽  
Machining Errors ◽  
Computer Numerically Controlled ◽  
Swept Volume

To address a major technical challenge in simulating geometric models of machined sculptured surfaces in three-axis virtual machining, this paper presents an efficient, accurate approach to representing the 3D envelopes of a cutter sweeping sequentially through cutter locations; these envelopes embody the furrow patches of the machined surfaces. In our research, the basic mechanism of removing stock material in three-axis computer numerically controlled (CNC) milling of sculptured surfaces is investigated, and, consequently, an effective model is proposed to represent the 3D envelopes (or furrow patches). Our main contribution is that a new directrix (or swept profile) of the furrow patches (mathematically, ruled surfaces) is identified as a simple 2D envelope of cutting circles and is formulated with a closed-form equation. Therefore, the 3D cutter-swept envelopes can be represented more accurately and quickly than the existing swept-volume methods. With this innovative approach, a method of accurate prediction of the machining errors along tool paths in three-axis finish machining is provided, which is then applied to the optimization of tool-path discretization in two examples. Their results demonstrate the advantages of our approach and verify that the current machining-error-prediction methods can cause gouging in three-axis sculptured surface milling.

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.

A Physical Machining Accuracy Predicting Model in Turning

2007 ◽  
Vol 329 ◽  
pp. 675-680 ◽  
Author(s):  
Sheng Fang Zhang ◽  
Zhi Hua Sha ◽  
Ren Ke Kang
Keyword(s):  
Manufacturing Process ◽  
Physical State ◽  
Cutting Parameters ◽  
Machining Process ◽  
Work Piece ◽  
Machining Accuracy ◽  
Predicting Model ◽  
Machining Precision ◽  
Machining Errors ◽  
Process System

During the Machining process of a part, along with the generation of new surfaces, various machining errors are produced. These machining errors depend on the characteristic of the manufacturing process system, as there are so many undetermined factors in the process system, it is very difficult to determine the machining accuracy of the workpiece. To the operator, the final accuracy of the part is very ambiguous, he can only consider the shape of the workpiece, and machining accuracy always be controlled by selecting different sets of cutting parameters. So the machining process is always time-consuming and costly. Therefore, it is very necessary to establish the accuracy predicting model to the workpiece. In this paper, According to the characteristic of turning, tool nose is abstracted into a “tangential point”, “three instantaneous centers” method is presented to get the reality shape of the workpiece. Using this method, and with the demarcating the errors in process system, the workpiece shaping model including multi-error is established. The model can not only describe the physical state of the workpiece, but also calculate the machining accuracy of the workpiece conveniently. In this paper, ‘three instantaneous centers’ method is developed to get a workpiece reality shape in turning. Using this method, the workpiece shaping model including multi-error is established. The model can not only describe the physical state of the work-piece, but also calculate the machining precision of the work-piece online.

scholarly journals Ultra-Precision Single-Point Diamond Turning of a Complex Sinusoidal Mesh Surface Using Machining Accuracy Active Control

2021 ◽  
Vol 67 (7-8) ◽  
pp. 343-351
Author(s):  
Peixing Ning ◽  
Ji Zhao ◽  
Shijun Ji ◽  
Jingjin Li ◽  
Handa Dai
Keyword(s):  
Active Control ◽  
Tool Path ◽  
Single Point ◽  
Diamond Turning ◽  
Machining Accuracy ◽  
Machining Error ◽  
Machined Surface ◽  
Mesh Surface ◽  
Slow Tool Servo ◽  
Radius Compensation

Single-point diamond turning (SPDT) assisted with slow tool servo (STS) is the most commonly utilized technique in the fabrication of optical modules. However, the tool path significantly affects the quality of the machined surface. In order to realize the determined machining accuracy effectively, a tool path generation (TPG) method based on machining accuracy active control (MAAC) is presented. The relationship between tool path and machining error is studied. Corner radius compensation (CRC) and the calculation of chord error and residual error are detailed. Finally, the effectiveness of the proposed approach is verified through a machining error simulation and a cutting experiment of a complex sinusoidal mesh surface fabrication.

The Improvement of the Machining Accuracy by Factor Analysis Approach

2012 ◽  
Vol 201-202 ◽  
pp. 333-336
Author(s):  
Zheng Hua Huang ◽  
Cheng Rong Jiang
Keyword(s):  
Factor Analysis ◽  
Machining Process ◽  
Analysis Approach ◽  
Machining Accuracy ◽  
Analysis Method ◽  
Machining Error ◽  
Error Sources ◽  
Machining Errors ◽  
Process System ◽  
Statistical Analysis Method

In machining, a complete machining process system consists of the machine tool, the fixture, the tool and the part together, the various errors are also inevitable. The factor analysis approach and the statistical analysis method were put forward to study the machining accuracy on the basis of the error sources analysis of the machining accuracy, and the measures were introduced to improve the machining accuracy by using the factor analysis approach. The change laws are grasped by the analysis of the machining errors, so as to take the appropriate measure to reduce the machining error and improve the machining accuracy.

A Generic, Geometric Approach to Accurate Machining-Error Predictions for 3-Axis CNC Milling of Sculptured Surface Parts: Part II — Applications and Analysis

2006 ◽  
Author(s):  
Zezhong C. Chen ◽  
Wei Cai
Keyword(s):  
Tool Path ◽  
Geometric Approach ◽  
Sculptured Surface ◽  
Cnc Milling ◽  
Sculptured Surfaces ◽  
Machining Error ◽  
Tool Paths ◽  
Machining Errors ◽  
Tool Surface ◽  
Cam Software

As sculptured surfaces are widely used in mechanical design, machining sculptured surface parts accurately is highly demanded in industry; however, it is quite challenging to meet their demand. Due to the geometric complexity of these surfaces, the tool-surface geometric mismatch always causes machining errors when the tool cuts along the tool paths. To prevent surface gouging, where the machining error is greater than the part tolerance, state-of-the-art CAM software usually determines cutter contact (CC) points on the tool paths first, and then simulates the machining to check the errors caused by this tool-surface mismatch. If surface gouging occurs, the CC points are adjusted using the CAM software. But this established method is quite time consuming and sometimes ineffective. To overcome these problems, a new system, based on the accurate predictions of machining errors, is proposed in this research paper for the optimization of CC points on the tool paths. First, two established CC point generation methods, the chordal deviation method and the circular arc approximation method, are introduced; and their limitations are addressed. Second, a sensitivity study of the machining errors with respect to the cutting tools is conducted. Then a system implementing the generic, geometric approach to accurate machining-error predictions is proposed to optimize CC points on the tool paths. Finally, this CC point optimization system is applied to two practical parts to demonstrate its advantages over the two established methods. This proposed work provides a profound understanding of the machining errors caused by the tool-surface mismatch and contributes to tool path planning for 3-axis CNC milling of sculptured surface parts.

Analysis of Machining Error in Numerical Control Milling

2013 ◽  
Vol 312 ◽  
pp. 710-713
Author(s):  
Jing Jun Cui
Keyword(s):  
Thermal Deformation ◽  
Numerical Control ◽  
Machining Accuracy ◽  
Machining Error ◽  
Important Indicator ◽  
Multiple Factors ◽  
Machining Errors ◽  
Cutter Wear ◽  
Finished Surface ◽  
Experimental Study Design

Generally speaking, the error in machining is an important indicator measuring the accuracy of finished surface. The machining error often occurs in numerical control milling. Such error will be influenced by multiple factors, such as cutter wear, thermal deformation, machine tool deformation, vibration or positioning error. Nowadays, though our science and technology develops rapidly, machining error problem in numerical control milling occurs frequently. At present, several methods can be applied to forecast machining error problems in numerical control milling, including on the basis of machining theory, experimental study, design study and artificial intelligence. The analysis and forecast of machining error problems in numerical control milling can to some extent improve the degree of machining errors so as to promote the machining accuracy in milling. The author expresses the views on machining error problems according to current situations of numerical control milling.

scholarly journals Effects of Machining Errors on Optical Performance of Optical Aspheric Components in Ultra-Precision Diamond Turning

Micromachines ◽  
2020 ◽  
Vol 11 (3) ◽  
pp. 331
Author(s):  
Yingchun Li ◽  
Yaoyao Zhang ◽  
Jieqiong Lin ◽  
Allen Yi ◽  
Xiaoqin Zhou
Keyword(s):  
Diamond Turning ◽  
Machining Accuracy ◽  
Aspheric Surface ◽  
Optical Performance ◽  
Machining Error ◽  
Optical Components ◽  
Optical Lens ◽  
Machining Errors ◽  
Ultra Precision ◽  
Multi Body

Optical aspheric components are inevitably affected by various disturbances during their precision machining, which reduces the actual machining accuracy and affects the optical performance of components. In this paper, based on the theory of multi-body system, we established a machining error model for optical aspheric surface machined by fast tool servo turning and analyzed the effect of the geometric errors on the machining accuracy of optical aspheric surface. We used the method of ray tracing to analyze the effect of the surface form distortion caused by the machining error on the optical performance, and identified the main machining errors according to the optical performance. Finally, the aspheric surface was successfully applied to the design of optical lens components for an aerial camera. Our research has a certain guiding significance for the identification and compensation of machining errors of optical components.

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