Contact Characteristics Analysis Of High-speed Spindle-tool Holder Cone Mating Interface Under Multi-load Coupling

The high-speed machine tool spindle parts is a key components of the high-speed spindle system.The high-speed spindle-tool holder connection as the most important part of the high-speed spindle system,its contact characteristics of the interface with the change of the high-speed spindle running status will present the problem,such as bending deformation and loose fit,which restricts the high-speed spindle rotation accuracy and vibration performance of the system,and finally influence the processing quality of the products.This paper aims at the contact characteristics of the spindle-tool holder conical mating interface of BT50 with taper of 7/24 to assume the boundary conditions of the spindle-tool holder conical mating interface from the point of view of the spindle-tool holder bearing multiple loads consistent with the actual working conditions and on the basis of elasticity.The theoretical models of the contact deformation of the spindle-tool holder interface under the coupling of axial force and centrifugal force were established respectively,and the finite element models of the spindle-tool holder interface under the coupling of axial force and centrifugal force,axial-centrifugal force and cutting force,axial-centrifugal force and spindle temperature rise and other multiple loads were established.The influences of the above factors on the contact characteristics of the high-speed spindle-tool holder interface were obtained.Finally,the accuracy of the finite element model of the high-speed spindle-tool holder interface under the action of multi-load coupling is verified through the rotation accuracy experiment of the high-speed spindle,which provides a theoretical basis for improving the connection performance of the high-speed spindle-tool holder system.The main research contents and results of this paper are as follows:(1)Theoretical model of the high-speed spindle-tool holder interface contact deformation.Under the given boundary condition 1 and 2,using the theory of elastic mechanics,the axial force and centrifugal force are established under the action of the high-speed spindle-tool holder with the axis of the interface contact deformation theory model.Under the two boundary: when the centrifugal force is fixed,the increase of the axial force can lead to the spindle's cone radial deformation quantity is large,the radial deformation of the handle cone down;when the axial force is fixed,the increase of the rotational speed will lead to the increase of the radial deformation of the cone of the spindle and the handle.(2)Finite element model of the high-speed spindle-tool holder contact characteristics under multi-load coupling.By using 4 order 44 nodes hexahedron grid cell parameters,such as shape function,the high-speed spindle-tool holder finite element model is established,and respectively analyzed the axial force and centrifugal force,centrifugal force and axial force and cutting force,the centrifugal force and axial force and under spindle temperature rise under the action of the high-speed spindle-tool holder's cone fitted interface contact deformation,stress,etc.It is found that the greater the cutting force is,the greater the radial deformation of the spindle cone is,and the smaller the radial deformation of the tool shank cone is.The higher the temperature rise of spindle,the smaller the contact deformation of spindle-tool holder interface.(3)Experimental comparison and verification of rotation accuracy of high-speed spindle system.The accuracy of the high-speed spindle-tool holder conical interface finite element model under multi-load coupling was verified by the experiments of spindle rotation accuracy with axial force of 15 k N and rotation speed of 6000,7000,8000,9000 and10000r/min respectively.