Compared with the traditional non-cutting measurement,machining tests can more accurately reflect the kinematic errors of five-axis machine tools in the actual machining process for the users.However,measurement and c...Compared with the traditional non-cutting measurement,machining tests can more accurately reflect the kinematic errors of five-axis machine tools in the actual machining process for the users.However,measurement and calculation of the machining tests in the literature are quite difficult and time-consuming.A new method of the machining tests for the trunnion axis of five-axis machine tool is proposed.Firstly,a simple mathematical model of the cradle-type five-axis machine tool was established by optimizing the coordinate system settings based on robot kinematics.Then,the machining tests based on error-sensitive directions were proposed to identify the kinematic errors of the trunnion axis of cradle-type five-axis machine tool.By adopting the error-sensitive vectors in the matrix calculation,the functional relationship equations between the machining errors of the test piece in the error-sensitive directions and the kinematic errors of C-axis and A-axis of five-axis machine tool rotary table was established based on the model of the kinematic errors.According to our previous work,the kinematic errors of C-axis can be treated as the known quantities,and the kinematic errors of A-axis can be obtained from the equations.This method was tested in Mikron UCP600 vertical machining center.The machining errors in the error-sensitive directions can be obtained by CMM inspection from the finished test piece to identify the kinematic errors of five-axis machine tool trunnion axis.Experimental results demonstrated that the proposed method can reduce the complexity,cost,and the time consumed substantially,and has a wider applicability.This paper proposes a new method of the machining tests for the trunnion axis of five-axis machine tool.展开更多
Metal-on-metal(MoM) hip replacements have proven to be a modern day orthopaedic failure. The early enthusiasm and promise of a hard, durable bearing was quickly quashed following the unanticipated wear rates. The rele...Metal-on-metal(MoM) hip replacements have proven to be a modern day orthopaedic failure. The early enthusiasm and promise of a hard, durable bearing was quickly quashed following the unanticipated wear rates. The release of metal ions into the blood stream has been shown to lead to surrounding soft tissue complications and early failure. The devastating destruction caused has led to a large number of revision procedures and implant extractions. The resulting research into this field has led to a new area of interest; that of the wear at the trunnion of the prosthesis. It had been previously thought that the metal debris was generated solely from the weight bearing articulation, however with the evolution of modularity to aid surgical options, wear at the trunnion is becoming more apparent. The phenomenon of "trunnionosis" is a rapidly developing area of interest that may contribute to the overall effect of metallosis in Mo M replacements but may also lead to the release of metal ions in non Mo M hip designs. The aim of this paper is to introduce, explain and summarise the evidence so far in the field of trunnionosis. The evidence for this phenomenon, the type of debris particles generated and a contrast between Mo M, non Mo M and resurfacing procedures are also presented.展开更多
基金Supported by National Nature Science Foundation of China(Grant No.51175461)Science Fund for Creative Research Groups of National Natural Science Foundation of China(Grant No.51221004)Program for Zhejiang Leading Team of S&T Innovation of China(Grant No.2009R50008)
文摘Compared with the traditional non-cutting measurement,machining tests can more accurately reflect the kinematic errors of five-axis machine tools in the actual machining process for the users.However,measurement and calculation of the machining tests in the literature are quite difficult and time-consuming.A new method of the machining tests for the trunnion axis of five-axis machine tool is proposed.Firstly,a simple mathematical model of the cradle-type five-axis machine tool was established by optimizing the coordinate system settings based on robot kinematics.Then,the machining tests based on error-sensitive directions were proposed to identify the kinematic errors of the trunnion axis of cradle-type five-axis machine tool.By adopting the error-sensitive vectors in the matrix calculation,the functional relationship equations between the machining errors of the test piece in the error-sensitive directions and the kinematic errors of C-axis and A-axis of five-axis machine tool rotary table was established based on the model of the kinematic errors.According to our previous work,the kinematic errors of C-axis can be treated as the known quantities,and the kinematic errors of A-axis can be obtained from the equations.This method was tested in Mikron UCP600 vertical machining center.The machining errors in the error-sensitive directions can be obtained by CMM inspection from the finished test piece to identify the kinematic errors of five-axis machine tool trunnion axis.Experimental results demonstrated that the proposed method can reduce the complexity,cost,and the time consumed substantially,and has a wider applicability.This paper proposes a new method of the machining tests for the trunnion axis of five-axis machine tool.
文摘Metal-on-metal(MoM) hip replacements have proven to be a modern day orthopaedic failure. The early enthusiasm and promise of a hard, durable bearing was quickly quashed following the unanticipated wear rates. The release of metal ions into the blood stream has been shown to lead to surrounding soft tissue complications and early failure. The devastating destruction caused has led to a large number of revision procedures and implant extractions. The resulting research into this field has led to a new area of interest; that of the wear at the trunnion of the prosthesis. It had been previously thought that the metal debris was generated solely from the weight bearing articulation, however with the evolution of modularity to aid surgical options, wear at the trunnion is becoming more apparent. The phenomenon of "trunnionosis" is a rapidly developing area of interest that may contribute to the overall effect of metallosis in Mo M replacements but may also lead to the release of metal ions in non Mo M hip designs. The aim of this paper is to introduce, explain and summarise the evidence so far in the field of trunnionosis. The evidence for this phenomenon, the type of debris particles generated and a contrast between Mo M, non Mo M and resurfacing procedures are also presented.
