Through analysis of the basic transformation of a typical body,the error transformations of the position vector and the displacement vector are employed,a general model for positioning errors of NC machine tools by us...Through analysis of the basic transformation of a typical body,the error transformations of the position vector and the displacement vector are employed,a general model for positioning errors of NC machine tools by using kinematics of the multi body system is discussed.By means of 8031 single chip system,intelligent error compensation controller has been developed.The results of experiments on XH714 machining center show that the positioning accuracy is enhanced effectively by more than 50%.展开更多
In order to improve the process precision of an XY laser annealing table, a geometric error modeling, and an identification and compensation method were proposed. Based on multi-body system theory, a geometric error m...In order to improve the process precision of an XY laser annealing table, a geometric error modeling, and an identification and compensation method were proposed. Based on multi-body system theory, a geometric error model for the laser annealing table was established. It supports the identification of 7 geometric errors affecting the annealing accuracy. An original identification method was presented to recognize these geometric errors. Positioning errors of 5 lines in the workspace were measured by a laser interferometer, and the 7 geometric errors were identified by the proposed algorithm. Finally, a software-based error compensation method was adopted, and a compensation mechanism was developed in a postprocessor based on LabVIEW. The identified geometric errors can be compensated by converting ideal NC codes to actual NC codes. A validation experiment has been conducted on the laser annealing table, and the results indicate that positioning errors of two validation lines decreased from ±37 μm and ±33 μm to ±5 μm and ±4.5 μm, respectively. The geometric error modeling, identification and compensation method presented in this work can be straightforwardly extended to any configurations of 2-dimensional worktable.展开更多
Do risingfactor prices promote technical efficiency （TE） in China＇s manufacturing sectors？ This topic has not yet been thoroughly studied in any literature. Using panel data from 1993 to 2007 of Chinese provinces...Do risingfactor prices promote technical efficiency （TE） in China＇s manufacturing sectors？ This topic has not yet been thoroughly studied in any literature. Using panel data from 1993 to 2007 of Chinese provinces＇ manufacturing industries, this paper calculated the TE by data envelopment analysis （DEA）. The result shows that China＇s manufacturing TE remained stagnate in the mid- and late-1990s and increased after 2000. Using a Pooled Regression Model, Fixed-effects Regression Model and Panel Corrected Standard Error （PCSE） to obtain robust parameters and the standard error, we find that rising factor prices have an obvious positive effect on the TE of the manufacturing industry and that this effect reaches its peak three to five years later. Therefore, the assumption of a ＂cost-Push TE＂ in China＇s manufacturing sectors can now be statistically proven. It has verified the significance of reforming China＇s faetor price system. Governments should value resource-allocating ej^iciency, implement policies that promote industrial transition and upgrading and transform the economic development pattern through technical innovation.展开更多
Error compensation is an effective method to improve the accuracy of NC machine tool.The compensation results are greatly affected by the error modeling and error measurement,so how to establish an accurate error mode...Error compensation is an effective method to improve the accuracy of NC machine tool.The compensation results are greatly affected by the error modeling and error measurement,so how to establish an accurate error model and accurately detect the geometric errors of machine tool are particularly important.In the paper,the volumetric error model of a multi-axis NC machine tool is established based on the multi-body system theory.The relative position deviations between the rotary axis and linear axis of the machine tool are considered in the modeling.To achieve quick and accurate detection,a laser tracker is based on the multi-station and time-sharing measurement principle to detect the geometric errors of machine tool,and each error of linear axis and rotary axis can be identified by this method.With the error model,error compensation can be carried out by modifying the machining process(G code),and the machining accuracy can be improved with the new G code.Experiment results show that the motion errors of a milling machine are significantly reduced after compensation,which verifies the effectiveness of compensation method.展开更多
In this paper,optimize-then-discretize,variational discretization and the finite volume method are applied to solve the distributed optimal control problems governed by a second order hyperbolic equation.A semi-discre...In this paper,optimize-then-discretize,variational discretization and the finite volume method are applied to solve the distributed optimal control problems governed by a second order hyperbolic equation.A semi-discrete optimal system is obtained.We prove the existence and uniqueness of the solution to the semidiscrete optimal system and obtain the optimal order error estimates in L ∞(J;L 2)-and L ∞(J;H 1)-norm.Numerical experiments are presented to test these theoretical results.展开更多
文摘Through analysis of the basic transformation of a typical body,the error transformations of the position vector and the displacement vector are employed,a general model for positioning errors of NC machine tools by using kinematics of the multi body system is discussed.By means of 8031 single chip system,intelligent error compensation controller has been developed.The results of experiments on XH714 machining center show that the positioning accuracy is enhanced effectively by more than 50%.
基金Projects(2012ZX04010-011,2009ZX02037-02) supported by the Key National Science and Technology Project of China
文摘In order to improve the process precision of an XY laser annealing table, a geometric error modeling, and an identification and compensation method were proposed. Based on multi-body system theory, a geometric error model for the laser annealing table was established. It supports the identification of 7 geometric errors affecting the annealing accuracy. An original identification method was presented to recognize these geometric errors. Positioning errors of 5 lines in the workspace were measured by a laser interferometer, and the 7 geometric errors were identified by the proposed algorithm. Finally, a software-based error compensation method was adopted, and a compensation mechanism was developed in a postprocessor based on LabVIEW. The identified geometric errors can be compensated by converting ideal NC codes to actual NC codes. A validation experiment has been conducted on the laser annealing table, and the results indicate that positioning errors of two validation lines decreased from ±37 μm and ±33 μm to ±5 μm and ±4.5 μm, respectively. The geometric error modeling, identification and compensation method presented in this work can be straightforwardly extended to any configurations of 2-dimensional worktable.
文摘Do risingfactor prices promote technical efficiency （TE） in China＇s manufacturing sectors？ This topic has not yet been thoroughly studied in any literature. Using panel data from 1993 to 2007 of Chinese provinces＇ manufacturing industries, this paper calculated the TE by data envelopment analysis （DEA）. The result shows that China＇s manufacturing TE remained stagnate in the mid- and late-1990s and increased after 2000. Using a Pooled Regression Model, Fixed-effects Regression Model and Panel Corrected Standard Error （PCSE） to obtain robust parameters and the standard error, we find that rising factor prices have an obvious positive effect on the TE of the manufacturing industry and that this effect reaches its peak three to five years later. Therefore, the assumption of a ＂cost-Push TE＂ in China＇s manufacturing sectors can now be statistically proven. It has verified the significance of reforming China＇s faetor price system. Governments should value resource-allocating ej^iciency, implement policies that promote industrial transition and upgrading and transform the economic development pattern through technical innovation.
基金supported by the National Natural Science Foundation of China (Grant No.51175415)the China Technology Major Project(Grant No.2011ZX04016-101)
文摘Error compensation is an effective method to improve the accuracy of NC machine tool.The compensation results are greatly affected by the error modeling and error measurement,so how to establish an accurate error model and accurately detect the geometric errors of machine tool are particularly important.In the paper,the volumetric error model of a multi-axis NC machine tool is established based on the multi-body system theory.The relative position deviations between the rotary axis and linear axis of the machine tool are considered in the modeling.To achieve quick and accurate detection,a laser tracker is based on the multi-station and time-sharing measurement principle to detect the geometric errors of machine tool,and each error of linear axis and rotary axis can be identified by this method.With the error model,error compensation can be carried out by modifying the machining process(G code),and the machining accuracy can be improved with the new G code.Experiment results show that the motion errors of a milling machine are significantly reduced after compensation,which verifies the effectiveness of compensation method.
基金supported by National Natural Science Foundation of China(Grant Nos.11261011,11271145 and 11031006)Foundation of Guizhou Science and Technology Department(Grant No.[2011]2098)+2 种基金Foundation for Talent Introduction of Guangdong Provincial UniversitySpecialized Research Fund for the Doctoral Program of Higher Education(Grant No. 20114407110009)the Project of Department of Education of Guangdong Province(Grant No. 2012KJCX0036)
文摘In this paper,optimize-then-discretize,variational discretization and the finite volume method are applied to solve the distributed optimal control problems governed by a second order hyperbolic equation.A semi-discrete optimal system is obtained.We prove the existence and uniqueness of the solution to the semidiscrete optimal system and obtain the optimal order error estimates in L ∞(J;L 2)-and L ∞(J;H 1)-norm.Numerical experiments are presented to test these theoretical results.
