With the high-speed and high-precision development of CNC machine tool, the vibration problem of ball screws linear guide feed unit has become more and more prominent. The dynamic characteristics was analyzed for ball screws linear guide feed unit, the 3D finite element model was built, the finite element modal analysis was discussed, the natural frequency and vibration modes were obtained, which were compared with the test results. The vibration weaknesses of ball screws linear guide feed unit were found out. The results show that the vibration weaknesses of ball screws linear guide feed unit occur mainly in the ball screws and its connection part with the worktable, its natural frequency are affected by its supporting pattern, and more close to the test results compared with those of ball screw feed unit without considering linear guide, which provide theoretical basis for the structure optimization of ball screws linear guide feed unit.

Axial contact stiffness increase of ball screws can reduce the vibration and enhance machining precision of CNC machine tool during machining process. On the basis of Hertz contact theory, calculation formula of axial contact stiffness was deduced with consideration of helix angle for 5010 single-nut and double-nut ball screws, influence factors comparison and analysis was carried out, and contrast curve was obtained. The result shows that the axial contact stiffness of preloaded double-nut ball screws is higher than that of single-nut ball screws. Ball number, contact angle and curvature ratio has obvious influence on the axial contact stiffness of double-nut ball screws: ball number increase can enhance the axial contact stiffness; increase of contact angle and curvature ratio can lower the axial contact stiffness. The axial contact stiffness of single-nut and double-nut ball screws does almost not vary with axial force and helix angle. The conclusion provides certain theoretical basis for design and selection of ball screws.

Ball screw is the key parts of NC machine, precise instrument and many kinds of mechanical devices. Whirlwind milling is a new and effective thread manufacture technology. This article studies the internal heat conduction equation of whirlwind milling ball screw based on Heat Transfer, calculates ANSYS simulation result. The simulation results show that the surface temperature distribution rule and internal temperature distribution rule of a ballscrew is consistent. The article analyzes the influence factors of the thermal elongation. It provides a basis for compensating the thermal deformation error of whirlwind milling ballscrew.

Whirlwind hard milling is a new high-efficient and environmental technology for maching process ballscrew thread. Thermal elongation of the workpiece in processing is one of the main reasons causing the screw-pitch error. The screw-pitch error due to thermal elongation caused by milling heat were analyzed . The dynamic temperature distribution simulation and thermal elogation of the workpiece were carried out with ANSYS software.Compared the simulation results with measured temperature during processing of the workpiece,the temperature distribution pattern is consistent.The result indicate that the law of thermal elongation of the free end and unprocessed section of ballscrew simulated by ANSYS is helpful to compensate screw-pitch error caused by thermal elogation.