Time filter

Source Type

Fan K.,University of Shanghai for Science and Technology | Yang J.,Shanghai JiaoTong University | Yang L.,Wulian Vocational Education Center
Mechanical Systems and Signal Processing | Year: 2015

To unify the error model for four types of CNC machining center, the comprehensive error model of each type of CNC machining center was established using the homogenous transformation matrix (HTM). The internal rules between the HTMs and the kinematic chains were analyzed in this research. The analysis results show that the HTM elements associated with the motion axes which are at the rear of the reference coordinate system are positive value. On the contrary, the HTM elements associated with the motion axes which are at the front of the reference coordinate system are negative value. To express these internal rules, the singular function was introduced to the HTMs. And a unified error model for four types of CNC machining center was established based on the HTM and the singular function. The unified error model includes 18 error elements which are the main factors affecting the machining accuracy of CNC machine tools. The practical results show that the unified error model is not only suitable for vertical machining center but also suitable for horizontal machining center. © 2015 Elsevier Ltd. All rights reserved.


Fan K.,Shanghai JiaoTong University | Yang J.,Shanghai JiaoTong University | Yang L.,Wulian Vocational Education Center
Advanced Science Letters | Year: 2012

The synthesis error is mainly related to the machine structure and the cutting process. Because the errors induced by the cutting process are related to the working conditions and the cutting parameters, the error model for the synthesis error should be a dynamic model which is suitable for various working conditions. To analyze the synthesis error, a series of twenty cutting tests were carried out, and the errors of the machined shafts were simulated by the back-propagation neural network (NN). Because the trained NN stores distributed information of the synthesis errors, the weights and bias of the trained NN were extracted and were programmed by the visual basic (VB). The macro program is employed to realize the synthesis error compensation under the various working conditions. Using the error compensation method, the maximum synthesis error of the machined shafts is reduced from 13.6 μm to 2.1 μm. The error is compensated by 92% compared with no compensation. © 2012 American Scientific Publishers. All rights reserved.


Fan K.,Shanghai JiaoTong University | Fan K.,Shanghai Dianji University | Yang J.,Shanghai JiaoTong University | Yang L.,Wulian Vocational Education Center
International Journal of Advanced Manufacturing Technology | Year: 2013

The spindle error and geometric error are the main sources of inaccuracy in CNC machining. With the rising of the machine tool parts' temperature, the spindle error and geometric error increase continually, and the error curves have a nonlinear distribution. To analyze the thermal effects on spindle error and geometric error, an experiment is carried out. To improve the machining accuracy of a CNC machine, an error model is proposed based on orthogonal polynomials. With the application of the orthogonal polynomials, the polynomial regression can be transformed into multiple linear regressions which are easier to calculate. In order to implement the real-time error compensation for the thermally induced spindle error and geometric error, an error compensation method is proposed based on the external coordinate offset. The thermally induced spindle and geometric error are compensated by 90 % compared with no compensation. © 2012 Springer-Verlag London Limited.


Fan K.,Shanghai JiaoTong University | Yang J.,Shanghai JiaoTong University | Yang L.,Wulian Vocational Education Center
Advanced Materials Research | Year: 2011

In CNC machining, various errors, which caused by the cutting process and the structure of the machine tool, affect the machining accuracy of the machined parts. To analyze the relationship among the cutting force induced error, the thermal deformation, and the tool wear induced error, the empirical formula is employed in this study. The result shows that the cutting force is the main factor which affects the error distribution of the machined parts; the thermal deformation and the tool wear induced error change the error distribution. Furthermore, all the errors are coupling each other. To improve the accuracy of the machined parts, a pre-compensation method is proposed. To achieve the real-time error compensation, an application is designed to calculate the coupling error and to generate the NC code. Using the pre-compensation method, the maximum error is reduced from 0.015 mm to 0.002 mm. The error is compensated by 86.7% compared with no compensation. © (2011) Trans Tech Publications, Switzerland.


Fan K.,Shanghai JiaoTong University | Yang J.,Shanghai JiaoTong University | Yang L.,Wulian Vocational Education Center
Advanced Materials Research | Year: 2011

The CNC milling machine is extensively used in manufacturing of the die and the box-type parts. However, the tool errors, which caused by the cutting heat and the cutting force, seriously affect the machining accuracy of the machined parts. Furthermore, the tool errors are too complex to be calculated by the empirical formula. To solve this problem, a tool error compensation method is proposed in this paper. The least-square method is employed to structure the error model. A weighting coefficient is proposed to adapt the various working conditions. The macro program is used to realize the real-time error compensation. Using the tool error compensation method, the maximum tool error is reduced from 0.053 mm to 0.005 mm. The error is compensated by 90.5% compared with no compensation. © (2011) Trans Tech Publications, Switzerland.


Fan K.,Shanghai JiaoTong University | Yang J.,Shanghai JiaoTong University | Yang L.,Wulian Vocational Education Center
Mechanical Systems and Signal Processing | Year: 2014

In this paper, a spatial error compensation method was proposed for CNC machining center based on the unified error model. The spatial error distribution was analyzed in this research. The result shows that the spatial error is relative to each axis of a CNC machine tool. Moreover, the spatial error distribution is non-linear and there is no regularity. In order to improve the modeling accuracy and efficiency, an automatic error modeling application was designed based on the orthogonal polynomials. To realize the spatial error compensation, a multi-thread parallel processing mode based error compensation controller was designed. Using the spatial error compensation method, the machine tools' accuracy is greatly improved compared to that with no compensation. © 2013 Elsevier Ltd.


Fan K.G.,Shanghai JiaoTong University | Yang J.G.,Shanghai JiaoTong University | Yang L.Y.,Wulian Vocational Education Center
Applied Mechanics and Materials | Year: 2013

The error modeling compensation method for improvement the machine tools' accuracy has been extensively used in the past decades. To unify the multi-error model for four types CNC machining center, the comprehensive multi-error model of TXYZ type machining center was established based on the homogenous coordinate transformation. According to the analysis of the transmission chain, a unified multi-error model for four types machining center was established based on the Singular Function. Using the unified multi-error model, the mathematical model of four types machining center can be standardized. It is very important for unceasing development of error compensation technology. © (2013) Trans Tech Publications, Switzerland.

Loading Wulian Vocational Education Center collaborators
Loading Wulian Vocational Education Center collaborators