Error Modeling and Iterative Algorithm for Compensation Instructions of Five-Axes NC Machine Tools Based on the Multi-Body System Theory

2013 ◽  
Vol 658 ◽  
pp. 287-291
Author(s):  
Li Gang Cai ◽  
Huai Qing Lu ◽  
Rui Luo ◽  
Qiang Cheng ◽  
Pei Hua Gu

The machining accuracy of NC machine can be improved significantly through the error compensation. The kernels of (multi-body system)MBS theories are that the number arrays of low-order body are used to describe the topological structures which are taken to generalize and refine MBS, and the characteristic matrix are employed to represent the relative positions and gestures between any two bodies in MBS. Based on the theory of rigid body dynamics and homogeneous coordinate transformation techniques, the space error model of five-axis gantry NC machine can be established, the modified NC instructions can be obtained and it prepares well ready for the software error compensation and the practical application. Gyratory motion of five-axis NC machine will generate the coupling of translational motion, so it is different from the three-axis NC machine in the process of error compensation and we need to decoupling.

2013 ◽  
Vol 321-324 ◽  
pp. 833-837
Author(s):  
Gao Feng Zhu ◽  
Yan Lei Zhang

Cause of machining error for NC Machine Tools is described, and principle of NC machinings error compensation on the basis of the existing in-line detection model of NC machine tools is analyzed in this paper. Regularity of error Modeling based on multi-body system is found,accordingly, we will find the corresponding characteristic matrix and transformation matrix if location features and sport features of the adjacent body are confirmed. Then, formula of error model is found, and we can get numerical solution and compensate error according to the identified error parameter. As a result, the machining accuracy of machine tools can be greatly improved.


2012 ◽  
Vol 241-244 ◽  
pp. 1470-1474 ◽  
Author(s):  
Hua Gang Han ◽  
Xiao Lin Hu ◽  
Ying Chun Li ◽  
Feng Shou Shang Guan

Based on multi-body system, the error model of gantry five-axis NC machine tools was discussed. The calculate method of precision process equation and NC instruction has been derived out. Based the above research works,make a emulate by using of geometry error compensation soft-ware. The result show machining precision can be improved through the error compensation method which is concluded in this paper.


2012 ◽  
Vol 271-272 ◽  
pp. 493-497
Author(s):  
Wei Qing Wang ◽  
Huan Qin Wu

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.


2014 ◽  
Vol 926-930 ◽  
pp. 478-481
Author(s):  
Jun Liang Liu ◽  
Zi Lun Li ◽  
Luo Cheng Li ◽  
Zi Jie Song

Against to the problem of widely used of software error compensation, raises error compensation device to instead of PC to realize erro r compensation. And introduces multi-body system relating to error compensation, represents the feasibility and implementation techniques of software error compensation using SCM. This program will show great values in the field of CNC.


2009 ◽  
Vol 626-627 ◽  
pp. 423-428
Author(s):  
Wei Sun ◽  
Hui Ma ◽  
Chao Feng Li ◽  
Bang Chun Wen

Based on the achievements of early works, a volumetric error modeling flow which is based on multi-body system theory is put forward. The flow includes 4 key steps mainly: describing structure, setting up coordinate system, creating characteristic matrix and generating volumetric error model are respectively. The operating method of every step is discussed in detail and the solving formula is given. At last, taking the VMC650 machining center of milling and boring which is developed by a machine tool factory as example, the validity of modeling flow is verified. This study can be used as a reference for opening automatic modeling system.


2010 ◽  
Vol 139-141 ◽  
pp. 1093-1096
Author(s):  
Xiu Shan Wang ◽  
Yan Li ◽  
Yong Chang Yu

The geometrical error modeling of the numerically controlled (NC) lathe is the key technique to kinematics design, precision analysis and error compensation. The study gives out the modeling process of the generally geometrical error model based on the multi-body system theory for the multi-axis NC machine tools. By the multi-system theory, using the low series body arrays to describe the complex mechanical system, the article has finished the geometrical error modeling of the numerically controlled lathe, analyzed the influence on the model of error of perpendicularity between the linear axes. The modeling method is highly-efficient and can not be affected by the structure of the NC machine tools. The error compensation and command correction can be implemented by the geometric errors model.


Author(s):  
Hongwei Liu ◽  
Rui Yang ◽  
Pingjiang Wang ◽  
Jihong Chen ◽  
Hua Xiang

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.


2011 ◽  
Vol 130-134 ◽  
pp. 2316-2320
Author(s):  
Ke Zhang ◽  
Zheng Xing Cui ◽  
Li Ya Gai ◽  
Peng Ge ◽  
Dong Gao Cai

NC machine plays an irreplaceable role in the modern manufacturing because of its high machining processing accuracy, quality stable, flexibility. Through using the Renishaw ML10 laser interferometer detect the positioning accuracy and repositioning accuracy of X axis and Z axis of the HTC20 series of NC machine tools. According to the detection result compensate NC system to meet the machining accuracy requirement. The result shows that the error compensation of NC system is a effective method to improve the position accuracy of NC machine.


2013 ◽  
Vol 690-693 ◽  
pp. 3244-3248
Author(s):  
Gui Qiang Liang ◽  
Ai Rong Zhang ◽  
Ting Ting Guo

In order to improve machining accuracy of machining center, the effect of geometric error on machining accuracy was researched by multi-body system theory. Taking a vertical machining center as example, topological structure of the machining center was described by lower body array. Geometric errors of the bodies in the multi-body system were expressed by homogeneous coordinate transformation. Error model for machining accuracy was deduced and geometric errors having great influence on the machining accuracy were identified. The research results show that, straightness errors and linear displacement errors in three directions have direct influence on machining accuracy, and the effect on machining accuracy caused by angle errors are related to the dimensions of the machining center and travel distance of the three axes. The research results provide guidance for analysis on sensitivity of geometric errors.


2014 ◽  
Vol 945-949 ◽  
pp. 1669-1672
Author(s):  
Jun Sun ◽  
Xing Liu ◽  
Zhi Xuan Li

Aiming to deal with thermal error of NC machine tool which can cause reduce of machining accuracy, this paper uses an external error compensation which interacts with NC controllers and PMAC multi-axis and then revises the tool path by adding the error tested in real-time by PMAC card. The processing accuracy is improved eventually. This method can compensate machine geometric errors and thermal errors in real-time. Comparing with other methods of error preventing, this method is more effective and affordable.


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