Ball screw axial stiffness of the bearing

Because of the screw in the process of work mainly bear axial force, the size of the axial force and axial stiffness of ball screw, the repositioning precision of the leadscrew, there are many factors that can affect screw axial stiffness, mainly includes: the axial stiffness of screw, the screw axial stiffness of supporting bearing and axial stiffness of ball nut, screw and the axial stiffness of the bearing, etc. China bearing network mainly discuss screw axial stiffness of supporting bearing and screw. 1, to understand the various bearing axial stiffness contrast size quite a thrust bearing axial stiffness is about angular contact ball bearings and tapered roller bearing axial stiffness of two times, maximum axial stiffness of thrust roller bearing, screw support with bearing axial stiffness between taper roller bearings, thrust cylindrical roller bearings. The axial stiffness big also means bigger starting torque. Can choose according to actual needs both economic and can satisfy the requirements of the bearing. Of course consider the bearing capacity and fatigue life of bearing, here is not to discuss. 2, screw support way and the effect of axial stiffness usually choose fixed screw drive on the supporting structure, so that we can reduce or eliminate screw and drive components of the joint, Parallel to the axial wrong, wrong, wrong) The impact on the screw position precision. With specific examples below to see the same screw with different ways to support its influence on the axial stiffness. CNC milling machine with ball screw feed mechanism, the average load Fa = 3000 n, choose CM5006 - 5 ball screw, screw length L = 1. 0m. Try to calculate screw in different support condition the influence of the axial stiffness. Ks = screw shaft axial stiffness ( KN /μm) d1 = 45。 2 mm diameter at the end of the screw ( mm） L0 = 1000 mm screw length L1 = 68 mm nut installation dimension E = 2. 06 * 10 ^ 5 mpa ( Screw modulus of elasticity) As = screw effective cross-sectional area ( mm^2） This analysis from the fixed end 100 mm to 800 mm screw within the scope of work axial stiffness influence on positioning accuracy. 1) Fixed - — Free this structure, support structure is suitable for the positioning accuracy is not high, screw rotational speed is low and ball nut from or by a very small radial force condition. 2) Fixed - — Simply supported this kind of structure, the support structure is suitable for the positioning accuracy is too high to afford the operation condition of the radial force is small, because the other end is simply supported, critical speed is higher than the fixed - — Free support. Because of the simply supported support can slide along the axial direction in a small range, so this way of support for the influence of the axial stiffness and fixed - - The same way free support. 3) Fixed - — Fixed support this way of supporting axial stiffness, high repeat positioning accuracy, can withstand the bigger radial load, normally this kind of structure but also exert a certain tension in advance on screw, the screw bear radial load capacity is greatly increased, and in the case of temperature, screw can also keep a certain tension in advance, so that even if has a temperature change, the change in temperature will not affect the length of the screw, just change the size of the screw inner stress. 【 Warm prompt. 【 The bearing network] Some information from the Internet, and strive to secure timely, accurate, aims to deliver more information, does not represent our views to its approval or responsibility for their authenticity. If this net reprint information involves the issues such as copyright, please contact with this net. Tel: 0571 - 81630205. Tags: production and processing