Error Compensation for Sculptured Surface Productions by the Application of Control-Surface Strategy Using Predicted Machining Errors

1997 ◽  
Vol 119 (3) ◽  
pp. 402-409 ◽  
Author(s):  
Ee Meng Lim ◽  
Chia-Hsiang Menq
Keyword(s):  
Error Compensation ◽  
Control Surface ◽  
Surface Generation ◽  
Production Cycle ◽  
Sculptured Surface ◽  
Generation Model ◽  
Machining Error ◽  
Geometry Model ◽  
Machining Errors ◽  
Developed Surface

In this paper, the principle and effectiveness of the control-surface strategy in machining-error compensation for end milling processes are studied. Using this strategy, two new approaches, namely the direct compensation approach and the sensitivity function approach, are proposed. When compared to existing approaches, there are two major improvements in the proposed approaches. First, machining errors caused by tool deflection are estimated from a developed surface generation model. This eliminates the time and costs required to design and conduct the actual machining experiments and dimensional inspections. Second, the effectiveness of the proposed approaches is improved either by increasing the number of times the strategy is been used or by selecting the appropriate shifted distance based on the estimated machining-error curve. The effectiveness of the proposed error-compensation approaches is verified from simulations and experimental results for a 2D sculptured surface. By using computer aided design tool, this surface generation model can be easily applied to the problems in which the designed surfaces are complex 3D sculptured by considering more complicated chip geometry model. These proposed approaches can also be integrated into an integrated framework for machining path planning in which prediction and compensation of dimensional errors take place in the process development phase rather than in the manufacturing phase of the production cycle.

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.

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.

A Machining Error Compensation Method Using on-Machine Profile Measurement in 3-Axis Aspheric Grinding

2010 ◽  
Vol 154-155 ◽  
pp. 390-395 ◽  
Author(s):  
Hao Huang ◽  
Xiang Yang Lei ◽  
Jian Wang ◽  
Qiao Xu ◽  
Liang Yu He ◽  
...  
Keyword(s):  
Measurement System ◽  
Error Compensation ◽  
Mutual Influence ◽  
Machining Accuracy ◽  
Profile Measurement ◽  
Precision Grinding ◽  
Machining Error ◽  
Machining Errors ◽  
Compensation Technique ◽  
Grinding Machine

The causes of machining errors are very complicated and apt to mutual influence in aspheric grinding, so it is difficult to improve machining accuracy by control one cause. To compensate the machining error of large aspheric grinding, an error-compensation technique using on-machine profile measurement system in three axes grinding machine are presented. To verify the effectiveness of the compensation machining and the reliability of the measurement system, experiments on high-precision grinding machine were performed. Moreover, the compensation machining with the on-machine measurement substantially decreases the machining errors and improve machining accuracy by more than 45%, compared with the non-compensation machining.

Analysis of Cutting Forces and Machining Error in Ball End Milling of Cylindrical Surfaces

2011 ◽  
Vol 328-330 ◽  
pp. 560-564
Author(s):  
Ba Sheng Ouyang ◽  
Guo Xiang Lin ◽  
Yong Hui Tang
Keyword(s):  
Cutting Forces ◽  
End Milling ◽  
Cutting Conditions ◽  
Machining Error ◽  
Machined Surface ◽  
Convex Surfaces ◽  
Machining Errors ◽  
End Mills ◽  
Tool Deflections ◽  
Cutting Modes

Cutting forces and machining error in contouring of concave and convex surfaces using helical ball end mills are theoretically investigated. The cutting forces are evaluated based on the theory of oblique cutting. The machining errors resulting from the tool deflections due to these forces are evaluated at various points of the machined surface. The influence of various cutting conditions and cutting modes on machining error is investigated and discussed.

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.

Cutting Path and Feedrate Optimization for Complex Surface Machining Using Ball End Milling Process

1995 ◽  
Author(s):  
Ee Meng Lim ◽  
Chia-Hsiang Menq ◽  
David W. Yen
Keyword(s):  
End Milling ◽  
Control Point ◽  
Local Maximum ◽  
Complex Surface ◽  
Milling Process ◽  
Surface Generation ◽  
Generation Model ◽  
Nc Programming ◽  
Machining Planning ◽  
Cutting Path

Abstract A new machining strategy, called cutting-path/adaptive-feedrate strategy, is proposed to improve the productivity of sculptured-surface productions subjected to force and dimensional constraints. In this proposed strategy, a new machining-planning aid, called maximum feedrate map, is developed. In this map, the maximum allowable feedrates at each control point along all machining directions subjected to the specified constraints are determined using a surface generation model. These local maximum-feedrate boundaries indicate the acceptable range of feedrates that a part programmer can use in the NC programming. In addition, the maximum feedrate map also provides the part programmer an important aid in selecting the cutting directions. The proposed strategy was applied to the machining planning for turbine blade die productions. Both computer simulation and experimental study were performed.

On-line first-order machining error compensation for thin-walled parts considering time-varying cutting condition

2021 ◽  
pp. 1-16
Author(s):  
Xiong Zhao ◽  
Lianyu Zheng ◽  
Yuehong Zhang
Keyword(s):  
Error Compensation ◽  
Compensation Method ◽  
Cutting Condition ◽  
Time Varying ◽  
Machining Error ◽  
Process Step ◽  
Compensation Model ◽  
First Order ◽  
On Line ◽  
Thin Walled

Abstract Mirror error compensation is usually employed to improve the machining precision of thin-walled parts. However, this zero-order method may result in inadequate error compensation, due to the time-varying cutting condition of thin-walled parts. To cope with this problem, an on-line first-order error compensation method is proposed for thin-walled parts. With this context, firstly, the time-varying cutting condition of thin-walled parts is defined with its in-process geometric and physical characteristics. Based on it, a first-order machining error compensation model is constructed. Then, during the process planning, the theory geometric and physical characteristic of thin-walled parts are respectively obtained with CAM software and structure dynamic modification method. After process performing, the real geometric characteristic of thin-walled parts is measured, and it is used to calculate the dimension error of thin-walled parts. Next, the error compensated value is evaluated based on the compensation model, from which, an error compensation plane is constructed to modify the tool center points for next process step. Finally, the machining error is compensated by performing the next process step. A milling test of thin-walled part is employed to verify the proposed method, and the experiment results shown that the proposed method can significantly improve the error compensation effect for low-stiffness structure, and thickness precision of thin-walled parts is improved by 71.4 % compared with the mirror error compensation method after machining.

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