Study On The Friction Wear And Wear Characteristics Of The Feed System For NC Machine Tools

With the development of modern mechanical manufacturing technology toward the direction of intelligentization,flexibility,integration and high automatization,which requires that the NC machines can still maintain some good characteristics,such as high accuracy,low noise,high reliability and long life in the case of high speed and overload.Ball screw mechanism as the one of the key features of NC machine tools,its friction and wear volume largely determines the precision of the NC machine tool and longevity.Ball screw mechanism at high speed,due to the axial load,relative sliding,surface roughness,etc.,can cause different degree of wear surface,it will be on the ball screw mechanism which reduces the accuracy,reliability and life and so on,makes the contact mechanics characteristics of ball screw pair research is particularly important.Based on Hertz contact theory and deformation compatibility condition,the establishment of the ball screw mechanism load distribution model,numerical calculation program developed contact load;Through numerical simulation,the paper analyzes the related parameters on the influence law of contact load of ball screw mechanism,and then puts forward the load spectrum compiling method,calculate the ball screw mechanism wear,feed system and accuracy stable life prediction method.The concrete research content is as follows:(1)Based on Hertz contact theory and the theory of differential geometry,established the ball screw mechanism of screw and nut on the surface of the raceway geometry equation;Using the theory of deformation coordination,nut ball screw mechanism load distribution model is established;Through numerical simulation,the paper analyzes the ball number,axial load of ball screw pair of load,the influence of the distribution features of the contact angle.(2)According to the load distribution of single nut ball screw pair theory,established the mathematical model of high-speed nut ball screw pair ball are brought forward in the screw nut extrusion cavity motion parameters of numerical calculation method,and the development of the corresponding MATLAB calculation,Through numerical calculation,the paper analyzes the leadscrew nut extrusion cavity axial load and feed rate on the influence between sliding velocity and contact Angle.(3)Based on the working process of the feed system and the torque of the servo motor current workbench position detection results along with the change of time,ball screw pair is given by the axial force changing with the workbench position;Using screw axial driving force,through numerical analysis to calculate the lead screw nut mechanism contact load along with the change of position,the corresponding load spectrum is compiled;Based on Archard wear theory of ball screw pair wear is calculated,and put forward the life span of the ball screw nut mechanism and accuracy stable prediction method.