A novel error compensation method for multistage machining processes based on differential motion vector sets of multiple contour points

2020 ◽  
pp. 1-23
Author(s):  
Mengrui Zhu ◽  
Guangyan Ge ◽  
Xiaobing Feng ◽  
Zhengchun Du ◽  
Jianguo Yang
Keyword(s):  
Error Compensation ◽  
Tool Path ◽  
Motion Vector ◽  
Zero Point ◽  
Compensation Method ◽  
Machining Processes ◽  
Machined Surface ◽  
Differential Motion ◽  
Variation Propagation ◽  
Workpiece Setup

Abstract Modeling the variation propagation based on the stream of variation (SoV) methodology for multistage machining processes (MMPs) has been investigated intensively in the past two decades, however little research is conducted on the variation reduction and the existing work fails to be applied to irregular features caused by the machining-induced variation varying with the positions of the contour points on the machined surface. This paper proposes a novel error compensation method for MMPs through modifying the tool path to reduce variation for general features. The method based on differential motion vector (DMV) sets of multiple contour points is presented to represent the deviation of the irregular feature. Then the conventional SoV model is further extended to more accurately describe variation propagation for irregular features considering the actual datum-induced variations and the varying machining-induced variations, especially the deformation errors for the low stiffness workpiece. Based on the extended SoV model and error equivalence mechanism, the datum error and fixture error are transformed to the equivalent tool path error. Then the original tool path is modified through shifting the machine zero point of machine tools with no need for changing the original G code and workpiece setup. A real cutting experiment validates the effectiveness of the proposed error compensation method for MMPs with an average precision improvement of over 60%. The application of the extended SoV model significantly contributes to compensating more complex error sources for MMPs, such as the clamp force, the internal residual stress, etc.

scholarly journals Variation propagation modelling in multistage machining processes using dual quaternions

2020 ◽  
Vol 111 (9-10) ◽  
pp. 2987-2998
Author(s):  
Filmon Yacob ◽  
Daniel Semere
Keyword(s):  
Motion Vector ◽  
Manufacturing Processes ◽  
Machining Processes ◽  
Dual Quaternions ◽  
Multistage Manufacturing ◽  
Differential Motion ◽  
Variation Propagation ◽  
Stream Of Variation ◽  
Matrix Differential ◽  
Propagation Modelling

Abstract Variation propagation models play an important role in part quality prediction, variation source identification, and variation compensation in multistage manufacturing processes. These models often use homogenous transformation matrix, differential motion vector, and/or Jacobian matrix to represent and transform the part, tool and fixture coordinate systems and associated variations. However, the models end up with large matrices as the number features and functional element pairs increase. This work proposes a novel strategy for modelling of variation propagation in multistage machining processes using dual quaternions. The strategy includes representation of the fixture, part, and toolpath by dual quaternions, followed by projection locator points onto the features, which leads to a simplified model of a part-fixture assembly and machining. The proposed approach was validated against stream of variation models and experimental results reported in the literature. This paper aims to provide a new direction of research on variation propagation modelling of multistage manufacturing processes.

scholarly journals A Novel Error Compensation Method of Five-axis Flank Milling of Ruled Surface by Modifying Tool Path

2021 ◽  
Author(s):  
Gaiyun He ◽  
Chenglin Yao ◽  
Yicun Sang ◽  
Yichen Yan
Keyword(s):  
Error Compensation ◽  
Tool Path ◽  
Error Distribution ◽  
Ruled Surface ◽  
Compensation Method ◽  
Distribution Model ◽  
Flank Milling ◽  
Average Error ◽  
Machining Accuracy ◽  
Five Axis

Abstract Five-axis flank milling is widely used in the aerospace and automotive industry. However, diverse sources of errors prevent the improvement of machining accuracy. This paper proposes a novel error compensation method for five-axis flank milling of ruled surface by modifying the original tool path according to the error distribution model. The method contains three steps: First, the errors at the middle of the straight generatrix on the machined surface are calculated according to error distribution, and the corresponding normal vectors are obtained by geometric calculation. Second, multi-peaks Gaussian fitting method is utilized to make connections between parameters in the original tool path and error distribution. Finally, the new tool path is generated by adjusting original tool path. Machining experiments are performed to test the effectiveness of the proposed error compensation method. The error distribution after compensation shows that the average error decreases 74%, and the maximum error (contains overcutting and undercutting) decreases 26%. Results show that the proposed error compensation method is effective to improve the accuracy for five-axis flank milling.

Correlating Surface Functionality with Machining Conditions in Precision Machining Processes

2004 ◽  
Vol 471-472 ◽  
pp. 112-116
Author(s):  
X.C. Luo ◽  
K. Cheng ◽  
R. Ward
Keyword(s):  
Surface Topography ◽  
Tool Path ◽  
Surface Generation ◽  
Force Model ◽  
Generation Model ◽  
Machining Processes ◽  
Machined Surface ◽  
Surface Functionality ◽  
Precision Turning ◽  
Machining Conditions

This paper attempts to correlate surface functionality generation with machining conditions by computer simulation and machining trials. The linear and nonlinear machining conditions, such as feed rate, built-up-edge, shear- localized chip formation, regenerative chatter are modelled in the light of their physical features. They are the inputs to the integrated surface topography generation model. The dynamic tool path is calculated through the dynamic cutting force model and surface response model. The surface is generated by transforming the tool profile onto the workpiece surface along the dynamic tool path. All of these models are integrated in a user-friendly Matlab Simulink environment. On the basis of the Simulink model, the dynamic simulation is performed to predict the 3D machined surface topography and its functionality. The simulation results have been validated by precision turning trials. The spectrum analysis of the machining dynamics and surface topography shows that surface generation is highly affected by the nonlinear factors in precision turning process. A case study shows the feasibility of generating some functional surface for some product/component through controlling machining variables.

An Error Compensation Method for Rectangular Window Based on NURBS Reconstruction Theory

2018 ◽  
Vol 917 ◽  
pp. 284-288
Author(s):  
Dong Xia Li ◽  
Ai Min Wang ◽  
Peng Hao Ren
Keyword(s):  
Software Development ◽  
Error Compensation ◽  
Tool Path ◽  
Measured Data ◽  
Compensation Method ◽  
Adaptive Compensation ◽  
Machining Error ◽  
Rectangular Window ◽  
B Splines ◽  
Error Calculation

Aiming at the error compensation problem for rectangular window, this paper presents a method of compensation for rectangular window based on NURBS (Non-Uniform Rational B-Splines) reconstruction. In the method, the machining surface is digitally obtained by means of on-machine measurement. The measured data are divided into four regions and different error compensation schemes are used for different regions. The adaptive compensation of the machining error calculated based on NURBS reconstruction theory is achieved by modifying the coordinates of the tool point in the cutter location file. The automation of error calculation and compensation is implemented by software development based on Visual Studio 2012. At the end of the paper, a compensating tool path is emulated in VERICUT. The results show our method is feasible.

scholarly journals Improvement of Simultaneous 5-Axis Controlled Machining Accuracy by CL-Data Modification

2019 ◽  
Vol 13 (5) ◽  
pp. 583-592
Author(s):  
Ryuta Sato ◽  
Kiichi Morishita ◽  
Isamu Nishida ◽  
Keiichi Shirase ◽  
Masanobu Hasegawa ◽  
...  
Keyword(s):  
Tool Path ◽  
Compensation Method ◽  
Control Mode ◽  
Machining Accuracy ◽  
Normal Vector ◽  
Geometrical Shape ◽  
Feed Speed ◽  
Machined Surface ◽  
Shape Accuracy ◽  
Controlled Motion

As the motion accuracy of 5-axis machining centers directly influences the geometrical shape accuracy of the machined workpieces, accuracy enhancement of the 5-axis machining centers is strongly needed. To improve the shape accuracy during the machining by a 5-axis machine tool, a method that modifies the CL-data based on the motion trajectory errors normal to the machined surface at each command point has been proposed. In this study, the proposed method is applied to simultaneous 5-axis controlled machining to improve motion accuracy. A normal vector calculation method for the simultaneous 5-axis controlled motion is newly proposed, and the compensation method is applied to turbine blade machining by 5-axis controlled motion. Measurement tests of the cutting motion for blade shape machining by a ball-end mill were carried out with a different control mode of NC. The CL-data for the machining tool path was also modified based on the calculated trajectory of the tool center point. Experimental results reveal that the feed speed and machining accuracy significantly depend on the control mode of NC, and that the shape accuracy can be improved by applying the proposed compensation method without any decrease in motion speed.

A modification of DMVs based state space model of variation propagation for multistage machining processes

2017 ◽  
Vol 37 (4) ◽  
pp. 381-390 ◽  
Author(s):  
Fuyong Yang ◽  
Sun Jin ◽  
Zhimin Li
Keyword(s):  
Current Model ◽  
Propagation Model ◽  
Machining Processes ◽  
Motion Vectors ◽  
Content Type ◽  
Model Based ◽  
Differential Motion ◽  
Variation Propagation ◽  
Current Variation ◽  
Differential Motion Vectors

Purpose Complicated workpiece, such as an engine block, has special rough locating datum features (i.e. six independent datum features) due to its complex structure. This locating datum error cannot be handled by current variation propagation model based on differential motion vectors. To extend variation prediction fields, this paper aims to solve the unaddressed variation sources to modify current model for multistage machining processes. Design/methodology/approach To overcome the limitation of current variation propagation model based on differential motion vectors caused by the unaddressed variation sources, this paper will extend the current model by handling the unaddressed datum-induced variation and its corresponding fixture variation. Findings The measurement results of the rear face with respect to the rough datum W and the pan face with respect to the hole Q by coordinate measuring machine (CMM) are −0.006 mm and 0.031 mm. The variation results for rear face and pan face predicted by the modified model are −0.009 mm and 0.025 mm, respectively. The discrepancy of model prediction and measurement is very small. Originality/value This paper modifies the variation propagation model based on differential motion vectors by solving the unaddressed variation sources, which can extend the variation prediction fields for some complicated workpiece and is useful in the future work for many fields, such as process monitoring, fault diagnosis, quality-assured setup planning and process-oriented tolerancing.

scholarly journals Automatic Error Compensation for Free-Form Surfaces by Using On-Machine Measurement Data

2019 ◽  
Vol 9 (15) ◽  
pp. 3073 ◽  
Author(s):  
Wei-chen Lee ◽  
Yu-tzu Lee ◽  
Ching-Chih Wei
Keyword(s):  
Error Compensation ◽  
Tool Path ◽  
Substantial Reduction ◽  
Measurement Data ◽  
Compensation Method ◽  
Numerical Control ◽  
Free Form ◽  
Machining Errors ◽  
Free Form Surfaces ◽  
Finishing Machining

Currently, most computer numerical control (CNC) controllers lack the function needed to compensate machining errors for free-form surfaces. The objective of this research was to enhance the accuracy and precision of the machined free-form surfaces of a workpiece using the mirror compensation method with the on-measurement data. By mirroring the points measured after semi-finishing, a new free-form surface for finishing machining can be automatically reconstructed. The surface can then be used to generate the cutting tool path to reduce the errors during finishing machining. In this research, three different types of surfaces were used for evaluating the proposed method. The results show that the proposed method reduced the standard deviations of the three surface geometries by 61%, 61%, and 32%, respectively. We also evaluated the tool radius modification method commonly used in the industry for error compensation and found that there is no substantial reduction on standard deviation. Therefore, the effectiveness of the error compensation method proposed in this research is evident.

State Space Modeling of Variation Propagation in Multistation Machining Processes Considering Machining-Induced Variations

2012 ◽  
Vol 134 (2) ◽  
Author(s):  
José V. Abellan-Nebot ◽  
Jian Liu ◽  
Fernando Romero Subirón ◽  
Jianjun Shi
Keyword(s):  
Tool Wear ◽  
Cutting Tool ◽  
Tolerance Allocation ◽  
Machining Processes ◽  
Process Diagnosis ◽  
Cutting Tool Wear ◽  
Differential Motion ◽  
Variation Propagation ◽  
Space Modeling ◽  
Stream Of Variation

In spite of the success of the stream of variation (SoV) approach to modeling variation propagation in multistation machining processes (MMPs), the absence of machining-induced variations could be an important factor that limits its application in accurate variation prediction. Such machining-induced variations are caused by geometric-thermal effects, cutting-tool wear, etc. In this paper, a generic framework for machining-induced variation representation based on differential motion vectors is presented. Based on this representation framework, machining-induced variations can be explicitly incorporated in the SoV model. An experimentation is designed and implemented to estimate the model coefficients related to spindle thermal-induced variations and cutting-tool wear-induced variations. The proposed model is compared with the conventional SoV model resulting in an average improvement on quality prediction of 67%. This result verifies the advantage of the proposed extended SoV model. The application of the new model can significantly extend the capability of SoV-model-based methodologies in solving more complex quality improvement problems for MMPs, such as process diagnosis and process tolerance allocation, etc.

Error correction technique for numerical control machine tools based on the simplex method

2021 ◽  
pp. 095440542110281
Author(s):  
Hongwei Liu ◽  
Rui Yang ◽  
Pingjiang Wang ◽  
Jihong Chen ◽  
Hua Xiang
Keyword(s):  
Machine Tool ◽  
Error Compensation ◽  
Simplex Method ◽  
Tool Path ◽  
Repeated Measurements ◽  
Numerical Control ◽  
Machining Accuracy ◽  
Correction Technique ◽  
Fluctuation Range ◽  
Nc Machine

The objective of this research is to develop a novel correction mechanism to reduce the fluctuation range of tools in numerical control (NC) machining. Error compensation is an effective method to improve the machining accuracy of a machine tool. If the difference between two adjacent compensation data is too large, the fluctuation range of the tool will increase, which will seriously affect the surface quality of the machined parts in mechanical machining. The methodology used in compensation data processing is a simplex method of linear programming. This method reduces the fluctuation range of the tool and optimizes the tool path. The important aspect of software error compensation is to modify the initial compensation data by using an iterative method, and then the corrected tool path data are converted into actual compensated NC codes by using a postprocessor, which is implemented on the compensation module to ensure a smooth running path of the tool. The generated, calibrated, and amended NC codes were immediately fed to the machine tool controller. This technique was verified by using repeated measurements. The results of the experiments demonstrate efficient compensation and significant improvement in the machining accuracy of the NC machine tool.

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