The dynamic performances of an ultra-precision fly cutting machine tool(UFCMT)has a dramatic impact on the quality of ultra-precision machining.In this study,the dynamic model of an UFCMT was established based on the ...The dynamic performances of an ultra-precision fly cutting machine tool(UFCMT)has a dramatic impact on the quality of ultra-precision machining.In this study,the dynamic model of an UFCMT was established based on the transfer matrix method for multibody systems.In particular,the large-span scale flow field mesh model was created;and the variation in linear and angular stiffness of journal and thrust bearings with respect to film thickness was investigated by adopting the dynamic mesh technique.The dynamic model was proven to be valid by comparing the dynamic characteristics of the machine tool obtained by numerical simulation with the experimental results.In addition,the power spectrum density estimation method was adopted to simulate the statistical ambient vibration excitation by processing the ambient vibration signal measured over a long period of time.Applying it to the dynamic model,the dynamic response of the tool tip under ambient vibration was investigated.The results elucidated that the tool tip response was significantly affected by ambient vibration,and the isolation foundation had a good effect on vibration isolation.展开更多
A deduced cutting force prediction model for circular end milling process is presented in this paper. Traditional researches on cutting force model usually focus on linear milling process which does not meet other cut...A deduced cutting force prediction model for circular end milling process is presented in this paper. Traditional researches on cutting force model usually focus on linear milling process which does not meet other cutting conditions, especially for circular milling process. This paper presents an improved cutting force model for circular end milling process based on the typical linear milling force model. The curvature effects of tool path on chip thickness as well as entry and exit angles are analyzed, and the cutting force model of linear milling process is then corrected to fit circular end milling processes. Instantaneous cutting forces during circular end milling process are predicted according to the proposed model. The deduced cutting force model can be used for both linear and circular end milling processes. Finally, circular end milling experiments with constant and variable radial depth were carried out to verify the availability of the proposed method. Experiment results show that measured results and simulated results corresponds well with each other.展开更多
The dynamics of an ultra‐precision machine tool determines the precision of the machined surface.This study aims to propose an effective method to model and analyze the dynamics of an ultra‐precision fly‐cutting ma...The dynamics of an ultra‐precision machine tool determines the precision of the machined surface.This study aims to propose an effective method to model and analyze the dynamics of an ultra‐precision fly‐cutting machine tool.First,the dynamic model of the machine tool considering the deformations of the cutter head and the lathe head is developed.Then,the mechanical elements are classified into M subsystems and F subsystems according to their properties and connections.The M‐subsystem equations are formulated using the transfer matrix method for multibody systems(MSTMM),and the F‐subsystem equations are analyzed using the finite element method and the Craig-Bampton reduction method.Furthermore,all the subsystems are assembled by combining the restriction equations at connection points among the subsystems to obtain the overall transfer equation of the machine tool system.Finally,the vibration characteristics of the machine tool are evaluated numerically and are validated experimentally.The proposed modeling and analysis method preserves the advantages of the MSTMM,such as high computational efficiency,low computational load,systematic reduction of the overall transfer equation,and generalization of its computational capability to general flexible‐body elements.In addition,this study provides theoretical insights and guidance for the design of ultra‐precision machine tools.展开更多
Based on the principle of Statistical Energy Analysis (SEA) for non-conservatively coupled systems under general excitations, relationship between noise radiated from and excitations on coupled complex structures is s...Based on the principle of Statistical Energy Analysis (SEA) for non-conservatively coupled systems under general excitations, relationship between noise radiated from and excitations on coupled complex structures is studied, which lays a foundation for the determination of noise/vibration energy by evaluation of exciting forces, and from that the quantitative analysis of the effects of an excitation on sound power from a sub-structure can be done. With extending of the relationship to the study of cutting noise, regression analysis method for evaluating the effects of cutting process on machine tool noise is established. Results show that cutting process has generally negligible effects on machine tool noise, and there is no apparent difference between machine tool noise in cutting condition and in idle one.展开更多
In order to solve the existing problems of current metal cutting equipment,combined with the development situation of metal cutting industry in China,on this basis,a design can realize multi-shaped metal cutting machi...In order to solve the existing problems of current metal cutting equipment,combined with the development situation of metal cutting industry in China,on this basis,a design can realize multi-shaped metal cutting machine tool. Introduces the working principle of the machine tool,the structure and parameters of the main component,and the establishment of the model by using the 3D modeling software Pro / Engineer（ Pro / E）;through listing the advantages of the mobile machine,shown that the metal machine tool has the structural characteristics of mobile,semi automated,can improve the cutting precision,increase cutting efficiency,and the utility market has certain value. It has guiding significance for the further study and the potential applications of the mobile cutting machine tool.展开更多
文摘The dynamic performances of an ultra-precision fly cutting machine tool(UFCMT)has a dramatic impact on the quality of ultra-precision machining.In this study,the dynamic model of an UFCMT was established based on the transfer matrix method for multibody systems.In particular,the large-span scale flow field mesh model was created;and the variation in linear and angular stiffness of journal and thrust bearings with respect to film thickness was investigated by adopting the dynamic mesh technique.The dynamic model was proven to be valid by comparing the dynamic characteristics of the machine tool obtained by numerical simulation with the experimental results.In addition,the power spectrum density estimation method was adopted to simulate the statistical ambient vibration excitation by processing the ambient vibration signal measured over a long period of time.Applying it to the dynamic model,the dynamic response of the tool tip under ambient vibration was investigated.The results elucidated that the tool tip response was significantly affected by ambient vibration,and the isolation foundation had a good effect on vibration isolation.
基金co-supported by Open National Natural Science Foundation of China(No.51005183)National Science and Technology Major Project(No.2011ZX04016031)China Postdoctoral Science Foundation(No.2012M521804)
文摘A deduced cutting force prediction model for circular end milling process is presented in this paper. Traditional researches on cutting force model usually focus on linear milling process which does not meet other cutting conditions, especially for circular milling process. This paper presents an improved cutting force model for circular end milling process based on the typical linear milling force model. The curvature effects of tool path on chip thickness as well as entry and exit angles are analyzed, and the cutting force model of linear milling process is then corrected to fit circular end milling processes. Instantaneous cutting forces during circular end milling process are predicted according to the proposed model. The deduced cutting force model can be used for both linear and circular end milling processes. Finally, circular end milling experiments with constant and variable radial depth were carried out to verify the availability of the proposed method. Experiment results show that measured results and simulated results corresponds well with each other.
基金National Natural Science Foundation of China,Grant/Award Number:52105129Science Challenge Project,Grant/Award Number:JZDD2016006–0102Boya Postdoctoral Fellowship of Peking University。
文摘The dynamics of an ultra‐precision machine tool determines the precision of the machined surface.This study aims to propose an effective method to model and analyze the dynamics of an ultra‐precision fly‐cutting machine tool.First,the dynamic model of the machine tool considering the deformations of the cutter head and the lathe head is developed.Then,the mechanical elements are classified into M subsystems and F subsystems according to their properties and connections.The M‐subsystem equations are formulated using the transfer matrix method for multibody systems(MSTMM),and the F‐subsystem equations are analyzed using the finite element method and the Craig-Bampton reduction method.Furthermore,all the subsystems are assembled by combining the restriction equations at connection points among the subsystems to obtain the overall transfer equation of the machine tool system.Finally,the vibration characteristics of the machine tool are evaluated numerically and are validated experimentally.The proposed modeling and analysis method preserves the advantages of the MSTMM,such as high computational efficiency,low computational load,systematic reduction of the overall transfer equation,and generalization of its computational capability to general flexible‐body elements.In addition,this study provides theoretical insights and guidance for the design of ultra‐precision machine tools.
文摘Based on the principle of Statistical Energy Analysis (SEA) for non-conservatively coupled systems under general excitations, relationship between noise radiated from and excitations on coupled complex structures is studied, which lays a foundation for the determination of noise/vibration energy by evaluation of exciting forces, and from that the quantitative analysis of the effects of an excitation on sound power from a sub-structure can be done. With extending of the relationship to the study of cutting noise, regression analysis method for evaluating the effects of cutting process on machine tool noise is established. Results show that cutting process has generally negligible effects on machine tool noise, and there is no apparent difference between machine tool noise in cutting condition and in idle one.
文摘In order to solve the existing problems of current metal cutting equipment,combined with the development situation of metal cutting industry in China,on this basis,a design can realize multi-shaped metal cutting machine tool. Introduces the working principle of the machine tool,the structure and parameters of the main component,and the establishment of the model by using the 3D modeling software Pro / Engineer（ Pro / E）;through listing the advantages of the mobile machine,shown that the metal machine tool has the structural characteristics of mobile,semi automated,can improve the cutting precision,increase cutting efficiency,and the utility market has certain value. It has guiding significance for the further study and the potential applications of the mobile cutting machine tool.
