The structure features and driving modes of virtual axis NC machine tools are studied. Accor ding to different application requirements,the three axis control method,the five axis control method and the sixfre...The structure features and driving modes of virtual axis NC machine tools are studied. Accor ding to different application requirements,the three axis control method,the five axis control method and the sixfreedom control method are put forward.These results lay a foundation for the product development of the virtual axis NC machine tools展开更多
Stribeck effect is regarded as the most important feed-axis friction characteristics. According to the relationship between friction and lubrication,a rapid technology for feed-axis lubrication condition evaluation of...Stribeck effect is regarded as the most important feed-axis friction characteristics. According to the relationship between friction and lubrication,a rapid technology for feed-axis lubrication condition evaluation of computer numerical control( CNC) machine tools based on soft sensor is proposed. To obtain its state information,the static friction force,Coulomb friction force,and viscous coefficient are used as the key parameters of the soft sensor for tread analysis. Then the various amplitude and velocity triangular wave test curve, and a precise nonlinear model identification method are presented. The results of the experiments analysis show that this method is feasible and reliable for evaluating feed-axis lubrication condition,which lays the foundation for on-line condition monitoring and reliability evaluation for feed-axis lubrication of machine tools.展开更多
A design approach for online pre-compensation of three-axis cross-coupled contour errors with mismatched dynamics is proposed.In the context of cross-coupled contour control design,online pre-compensation of contour e...A design approach for online pre-compensation of three-axis cross-coupled contour errors with mismatched dynamics is proposed.In the context of cross-coupled contour control design,online pre-compensation of contour errors is commonly employed.However,establishing a specific relationship between contour errors is challenging for mismatched computer numerical control(CNC)systems.Therefore,the design of interpolation methods for mismatched systems remains crucial,as most existing systems struggle to be adjusted to match seamlessly.This study introduces an online pre-compensation scheme for cross-coupled contour errors in three-axis motion,which constitutes a compensation system for real-time correction of contour error estimation.The coupling control structure,based on a speed loop,comprises a proportion integration differentiation(PID)control feedback controller,a feedforward controller,and an online pre-compensation cross-coupled contour controller.The experimental results demonstrate that the proposed three-axis cross-coupled contour error pre-compensation scheme significantly enhances the contour accuracy compared to traditional cross-coupled control systems.Moreover,the proposed cross-coupled contour error pre-compensation controller exhibits superior contour performance over conventional cross-coupled controllers when tracking high-order curvature bending paths.展开更多
In this paper,optimum positioning of cylindrical cutter for five-axis flank milling of non-developable ruled surface is addressed from the perspective of surface approximation.Based on the developed interchangeability...In this paper,optimum positioning of cylindrical cutter for five-axis flank milling of non-developable ruled surface is addressed from the perspective of surface approximation.Based on the developed interchangeability principle,global optimization of the five-axis tool path is modeled as approximation of the tool envelope surface to the data points on the design surface following the minimum zone criterion recommended by ANSI and ISO standards for tolerance evaluation.By using the signed point-to-surface distance function,tool path plannings for semi-finish and finish millings are formulated as two constrained optimization problems in a unified framework.Based on the second order Taylor approximation of the distance function,a sequential approximation algorithm along with a hierarchical algorithmic structure is developed for the optimization.Numerical examples are presented to confirm the validity of the proposed approach.展开更多
The following questions are discussed: feature cluster, feature clusterconcept and the reasoning formula. The defect based on approach direction and feed direction areanalyzed. Feature tool axis direction concept and ...The following questions are discussed: feature cluster, feature clusterconcept and the reasoning formula. The defect based on approach direction and feed direction areanalyzed. Feature tool axis direction concept and its definition method are submitted. The featurefor practical part is also clustered by tool axis direction.展开更多
文摘The structure features and driving modes of virtual axis NC machine tools are studied. Accor ding to different application requirements,the three axis control method,the five axis control method and the sixfreedom control method are put forward.These results lay a foundation for the product development of the virtual axis NC machine tools
基金National Natural Science Foundation of China(No.51305324)
文摘Stribeck effect is regarded as the most important feed-axis friction characteristics. According to the relationship between friction and lubrication,a rapid technology for feed-axis lubrication condition evaluation of computer numerical control( CNC) machine tools based on soft sensor is proposed. To obtain its state information,the static friction force,Coulomb friction force,and viscous coefficient are used as the key parameters of the soft sensor for tread analysis. Then the various amplitude and velocity triangular wave test curve, and a precise nonlinear model identification method are presented. The results of the experiments analysis show that this method is feasible and reliable for evaluating feed-axis lubrication condition,which lays the foundation for on-line condition monitoring and reliability evaluation for feed-axis lubrication of machine tools.
文摘A design approach for online pre-compensation of three-axis cross-coupled contour errors with mismatched dynamics is proposed.In the context of cross-coupled contour control design,online pre-compensation of contour errors is commonly employed.However,establishing a specific relationship between contour errors is challenging for mismatched computer numerical control(CNC)systems.Therefore,the design of interpolation methods for mismatched systems remains crucial,as most existing systems struggle to be adjusted to match seamlessly.This study introduces an online pre-compensation scheme for cross-coupled contour errors in three-axis motion,which constitutes a compensation system for real-time correction of contour error estimation.The coupling control structure,based on a speed loop,comprises a proportion integration differentiation(PID)control feedback controller,a feedforward controller,and an online pre-compensation cross-coupled contour controller.The experimental results demonstrate that the proposed three-axis cross-coupled contour error pre-compensation scheme significantly enhances the contour accuracy compared to traditional cross-coupled control systems.Moreover,the proposed cross-coupled contour error pre-compensation controller exhibits superior contour performance over conventional cross-coupled controllers when tracking high-order curvature bending paths.
基金Supported by the National Natural Science Foundation of China(Grant Nos.50775147 and 50835004)the National Basic Research Program of China("973"Project)(Grant No.2005CB724103)the Science&Technology Commission of Shanghai Municipality(Grant No.07JC14028)
文摘In this paper,optimum positioning of cylindrical cutter for five-axis flank milling of non-developable ruled surface is addressed from the perspective of surface approximation.Based on the developed interchangeability principle,global optimization of the five-axis tool path is modeled as approximation of the tool envelope surface to the data points on the design surface following the minimum zone criterion recommended by ANSI and ISO standards for tolerance evaluation.By using the signed point-to-surface distance function,tool path plannings for semi-finish and finish millings are formulated as two constrained optimization problems in a unified framework.Based on the second order Taylor approximation of the distance function,a sequential approximation algorithm along with a hierarchical algorithmic structure is developed for the optimization.Numerical examples are presented to confirm the validity of the proposed approach.
基金National Natural Science Foundation of China (No.59875006).
文摘The following questions are discussed: feature cluster, feature clusterconcept and the reasoning formula. The defect based on approach direction and feed direction areanalyzed. Feature tool axis direction concept and its definition method are submitted. The featurefor practical part is also clustered by tool axis direction.
